QUETTA, Pakistan: The most explosive question about the Taliban resurgence here along the border between Afghanistan and Pakistan is this: Have Pakistani intelligence agencies been promoting the Islamic insurgency?

The government of Pakistan vehemently rejects the allegation and insists that it is fully committed to help American and NATO forces prevail against the Taliban militants who were driven from power in Afghanistan in 2001.

Western diplomats in both countries and Pakistani opposition figures say that Pakistani intelligence agencies - in particular the powerful Inter-Services Intelligence and Military Intelligence - have been supporting a Taliban restoration, motivated not only by Islamic fervor but also by a longstanding view that the jihadist movement allows them to assert greater influence on Pakistan's vulnerable western flank.

More than two weeks of reporting along this frontier, including dozens of interviews with residents on each side of the porous border, leaves little doubt that Quetta is an important base for the Taliban, and found many signs that Pakistani authorities are encouraging the insurgents, if not sponsoring them.

The evidence is provided in fearful whispers, and it is anecdotal.

At Jamiya Islamiya, a religious school here in Quetta, Taliban sympathies are on flagrant display, and residents say students have gone with their teachers' blessings to die in suicide bombings in Afghanistan.

Three families whose sons had died as suicide bombers in Afghanistan said they were afraid to talk about the deaths because of pressure from Pakistani intelligence agents. Local people say dozens of families have lost sons in Afghanistan as suicide bombers and fighters.

One former Taliban commander said in an interview that he had been jailed by Pakistani intelligence officials because he would not go to Afghanistan to fight. He said that, for Western and local consumption, his arrest had been billed as part of Pakistan's crackdown on the Taliban in Pakistan. Former Taliban members who have refused to fight in Afghanistan have been arrested - or even mysteriously killed - after resisting pressure to re-enlist in the Taliban, Pakistani and Afghan tribal elders said.

"The Pakistanis are actively supporting the Taliban," declared a Western diplomat in an interview in Kabul. He said he had seen an intelligence report of a recent meeting on the Afghan border between a senior Taliban commander and a retired colonel of the Pakistani Inter-Services Intelligence.

Pakistanis and Afghans interviewed on the frontier, frightened by the long reach of Pakistan's intelligence agencies, spoke only with assurances that they would not be named. Even then, they spoke cautiously.

The Pakistani military and intelligence services have for decades used religious parties as a convenient instrument to keep domestic political opponents at bay and for foreign policy adventures, said Husain Haqqani, a former adviser to several of Pakistan's prime ministers and the author of a book on the relationship between the Islamists and the Pakistani security forces.

The religious parties recruited for the jihad in Kashmir and Afghanistan from the 1980s, when the Pakistani intelligence agencies ran the resistance by the mujahedeen and channeled money to them from the United States and Saudi Arabia to fight the Soviet Union in Afghanistan, Mr. Haqqani said.

In return for help in Kashmir and Afghanistan the intelligence services would rig votes for the religious parties and allow them freedom to operate, he said.

"The religious parties provide them with recruits, personnel, cover and deniability," Mr. Haqqani said in a telephone interview from Washington, where he is now a visiting scholar at the Carnegie Endowment for International Peace.

The Inter-Services Intelligence once had an entire wing dedicated to training jihadis, he said. Today the religious parties probably have enough of their own people to do the training, but, he added, the I.S.I. so thoroughly monitors phone calls and people's movements that it would be almost impossible for any religious party to operate a training camp without its knowledge.

"They trained the people who are at the heart of it all, and they have done nothing to roll back their protégés," Mr. Haqqani said.

After the Sept. 11, 2001, attacks in the United States, President Pervez Musharraf, under strong American pressure, pledged to help root out Islamic extremism, and, as both head of the army and president, he has more direct control of the intelligence services than past civilian prime ministers. But according to several analysts, Pakistani intelligence officials believe it is more prudent to prepare for the day when Western troops leave Afghanistan.

Pakistan has long seen jihadi movements like the Taliban as a counter to Indian and Russian influence next door in Afghanistan, the Western diplomat and other analysts said, and as a way to provide Pakistan with "strategic depth," or a friendly buffer on its western border.

In Pashtunabad, a warren of high mud-brick walls and narrow lanes in Quetta, the links of the government, religious parties and Taliban commanders to a local madrasa are thinly hidden, said a local opposition party member who lives in the neighborhood.

Three students from the madrasa went to Afghanistan recently on suicide missions, he said. The family of one of the men admitted that he had blown himself up but denied that he had attended the school. The man's brother suggested that he had been forced into the mission and that someone had recruited him for payment.

"Nowadays people are getting money from somewhere and they are killing other people's children," he said. "We are afraid of this government," he said. His father said he feared the same people would try to take his other son and asked that no family names be used. President Musharraf relies on the religious party Jamiat Ulema-i-Islam, or J.U.I., which dominates this province, Baluchistan, as an important partner in the provincial and national parliaments.

At a madrasa, called simply Jamiya Islamiya, on winding Hajji Ghabi Road, a board in the courtyard proudly declares "Long Live Mullah Omar," in praise of the Taliban leader, and "Long Live Fazlur Rehman," the leader of J.U.I.

Members of the provincial government and Jamiat Ulema-i-Islam are frequent visitors to the school, the local opposition party member said, asking that his name not be used because he feared Pakistan's intelligence services. People on motorbikes with green government license plates visit at night, he said, as do luxurious sport utility vehicles with blackened windows, a favorite of Taliban commanders.

Maulvi Noor Muhammad, a Jamiat Ulema-i-Islam representative from Baluchistan in the National Assembly, recently received a guest barefoot while sitting on the floor of a grubby district office in Quetta, a map of the world above him painted on the wall to represent his belief in worldwide Islamic revolution.

He denied providing the militants any logistical support. "The J.U.I. is not supporting the Taliban anymore," he said. "We are only providing moral support. We pray for their success in ousting the foreign troops from the land of Afghanistan."

On a recent morning, the deputy director of the Jamiya Islamiya madrasa, Qari Muhammad Ibrahim, declined to meet a female reporter for The New York Times but answered a question from a local male reporter.

He did not deny that some of the madrasa's 280 students had gone to fight in Afghanistan. "In the Koran it is written that it is every Muslim's right to fight jihad," he said. "All we are telling them is what is in the Koran, and then it's up to them to go to jihad." NATO officials and Western diplomats in Afghanistan have grown increasingly critical of Pakistan for allowing the Taliban leaders, commanders and soldiers to operate from their country, which has given an advantage to the insurgency in southern Afghanistan. In September, Gen. James L. Jones, then NATO's supreme commander, told the Senate Foreign Relations Committee that Quetta remained the headquarters of the Taliban movement.

Still, Pakistan has insisted that the Taliban leadership is not based in Quetta. "If there are Taliban in Quetta, they are few," said Pakistan's minister for information and broadcasting, Tariq Azim Khan. "You can count them on your fingers."

American officials and Western diplomats noted that, when put under enough pressure, Pakistan had come through with flashes of cooperation. But that only seems to reinforce the view that Pakistan's intelligence agencies are more in touch with what is going on in the Taliban insurgency than the government lets on publicly.

For instance, a senior Taliban leader, Mullah Akhtar Muhammad Osmani, who operated on both sides of the border, was killed in an airstrike in Afghanistan on Dec. 19, after Pakistan helped track him, an American official in Afghanistan said.

At the same time, a kind of dirty war is building between Afghan and Pakistani intelligence agencies. A senior Afghan intelligence official said one of its informers in Pakistan was recently killed and dumped in pieces in Peshawar, a border town. The Afghan intelligence service has also recently arrested two Afghan generals, one retired, who have been charged with spying for Pakistan, as well as a Pakistani suspected of being an intelligence agent. President Musharraf has acknowledged that some retired Pakistani intelligence officials may still be involved in supporting their former protégés in the Taliban.

Hamid Gul, the former director general of Pakistani intelligence, remains a public and unapologetic supporter of the Taliban, visiting madrasas and speaking in support of jihad at graduation ceremonies.

Afghan intelligence officials recently produced a captured insurgent who said Mr. Gul facilitated his training and logistics through an office in the Pakistani town of Nowshera, in the North-West Frontier Province, west of the capital, Islamabad.

NATO and American officials in Afghanistan say there is also evidence of support from current midlevel Pakistani intelligence officials. Just how far up that support reaches remains in dispute.

At least five villages in Pishin, a district northwest of Quetta that stretches toward the Afghan border, lost sons in the recent fighting in Kandahar between the Taliban and NATO forces, opposition politicians said.

One village, Karbala, is a main center of support for the jihad, local people say. Unlike the other villages, which blend into the stark desertlike landscape with their mud-brick houses and compound walls, Karbala has lavish houses, mosques and madrasas, suggesting an unusual wealth.

Farther on, in the village of Bagarzai, lies the grave of Azizullah, a religious scholar who used only one name and acquired fame as a Taliban commander.

Only 25, he was killed with a group of 15 to 20 men in an airstrike in the Afghan province of Helmand on May 22, said his father, Hajji Abdul Hai. Thousands of people attended his funeral, including senior members of the provincial government, the father said.

Mr. Hai, 50, who is a Jamiat Ulema-i-Islam member, denied that his son had been persuaded to fight by anyone. "From the start it was his spirit to take part in jihad," his father said. "It's all to do with personal will. If someone agrees, then he goes. Even if someone wishes to, no one can stop him."

It is an argument that supporters of the jihad use frequently. But for some of the families mourning their sons, there is no doubt that the madrasas and the religious parties are the first point of contact.

That was the conclusion reached by the family of Muhammad Daoud, a 22-year-old man from Pishin who disappeared more than a year ago.

"In our search we went to many places and everyone said different things," said his father, Hajji Noora Gul. "We went to the madrasa in Pashtunabad, but no one was ready to tell us his whereabouts."

"Even the madrasa people did not know," he added. "Behind the curtain of the madrasa, maybe there are other people who do this. Maybe there are some businessmen who take them." Then, he said, a Taliban propaganda CD came out showing his son with a group of others taking an oath before the Taliban commander, Mullah Dadullah.

"He had a shawl over his head and was preparing for a suicide bombing," Mr. Gul said. "He said, 'I am fighting for God, and I am ready for this.' "

His eldest son, Allah Dad, 33, blamed the jihadi groups and the Inter-Services Intelligence. "We don't know how he made contact with those jihadi groups," he said. "There are some groups active in taking people to Afghanistan and they are active in Quetta. "All Taliban are I.S.I. Taliban," he added. "It is not possible to go to Afghanistan without the help of the I.S.I. Everyone says this."

David Rohde contributed reporting from Kabul, Afghanistan.