PESHAWAR, PAKISTAN -- In the two years since they seized power, Pakistan's military rulers have banned rallies and arrested protesters. But there is one group they have never dared to touch: the powerful Muslim militants who have millions of supporters and sympathizers here.

The militants, including many trained at Pakistan's 6,000 religious seminaries, are a crucial pillar of support for the Afghan Taliban regime that has sheltered Osama bin Laden, the prime suspect as mastermind of the devastating terrorist attacks last week.

The hard-line Muslims are such an influential force in Pakistan, with sympathizers even in the senior ranks of the military, that they are threatening a mass uprising to disrupt Pakistan's support for the expected U.S.-led attack on terrorist suspects in neighbouring Afghanistan.

Their burgeoning power has forced the Pakistani regime to walk a cautious line in its co-operation with U.S. plans for military retaliation. Their power also helps to explain why Mr. bin Laden and his Taliban protectors have enjoyed substantial military support from the Pakistan government.

A few months ago, the Muslim militants staged an astonishing show of strength. They mobilized 200,000 men for a three-day gathering near the city of Peshawar, only about 60 kilometres from the Afghan border.

While other public rallies had been banned, the Pakistani authorities didn't ban this one, where huge crowds vowed a holy war and chanted threats of death to the United States. Vendors hawked posters of Mr. bin Laden and depictions of a U.S. flag in flames.

About 30 Taliban officials were there. The crowd heard messages of support from the Taliban leader, Mullah Mohammed Omar, and from Mr. bin Laden himself, who boasted that Afghanistan is the only country in the world with a true Islamic system.

While the Muslim hard-liners have never mustered more than a small percentage of the vote in Pakistani elections, they have intimidated the government with their ability to mobilize crowds of fanatical followers.

There are even fears that the militants could seize power violently if Pakistan's government provokes their fury by supporting U.S. attacks on the Taliban.

Some analysts say the Muslim militants are on the verge of pushing much closer to the seat of power. One of the leading militant groups recently announced that it has purchased thousands of hectares of land for a new religious university near the Pakistani capital, Islamabad, where the major government ministries are located. The university would make it easier for the militants to mobilize thousands of young men to apply direct pressure on the Pakistani government at any moment, analysts say.

"It will be a cover for all kinds of militant elements," I. A. Rehman, director of the Human Rights Commission of Pakistan, said.

"It has very serious implications. The location is dangerous. Several thousand people will be available to march on the government at any time. . . . There is a struggle for power going on, and the militants believe that a show of strength will help them capture the system."

There are many signs that the militants are gaining ground in their campaign to establish a Taliban-style theocratic state in Pakistan, Mr. Rehman said. In some provinces, the militants have won parliamentary seats previously held by traditional feudal leaders. More worrying, a number of high-ranking military officers and influential former generals have been elected as representatives of militant parties, he said.

All of this helps explain why Pakistan, despite its official denials, has been funnelling military aid to the Taliban: providing military training; allowing it to recruit fighters from Pakistani madrassas (schools); and allowing Taliban weapons to be transported to Afghanistan through Pakistan's territory, according to recent reports by Human Rights Watch, an independent organization based in New York.

The reports say senior Pakistani military and intelligence officers were helping plan Taliban military operations, Pakistani aircraft were assisting in Taliban troop rotations, former Pakistani military officers were helping the Taliban maintain and operate artillery weapons, and that Pakistan was allowing Taliban recruits to cross its border into Afghanistan without interference.

Pakistani military and intelligence officers, based in a guarded compound near Kabul, have given weapons training to Taliban recruits from Pakistan, according to Human Rights Watch. It also says that private Pakistani companies, often run by former military officers, have purchased weapons and ammunition for the Taliban from dealers in Hong Kong and Dubai.

The reports say that Pakistan was also heavily involved in soliciting money for the Taliban and bankrolling its operations.