A Pakistani Taliban commander has ordered his men to withdraw from Buner district, a spokesman said on Friday, amid mounting alarm in the United States over the Taliban advance toward the capital of the nuclear-armed Muslim state.

Taliban spokesman Muslim Khan said there were around 100 fighters in Buner, a valley just 100 km (60 miles) from Islamabad and less than five hours drive from the capital.

"Our leader has ordered that Taliban should immediately be called back from Buner," Khan told Reuters.

Khan belongs to a faction led by Fazlullah, the Taliban commander in neighboring Swat valley, where the government has caved in to militants' demands for the imposition of Islamic law.

He said government and Taliban representatives were en route to Buner, along with Maulana Sufi Mohammad, a radical Muslim cleric who brokered the Swat deal, to deliver a message to fighters to vacate the district.

Khan was quoted in the past week as saying al Qaeda would be given refuge in lands under Taliban control.

US Secretary of State Hilary Clinton said Pakistan's policies in Swat abdicated authority to the Taliban, while Defence secretary Robert Gates urged Pakistani leaders to act against foes who posed an "existential threat" to the state.

Earlier this month parliament forced a reluctant president Asif Ali Zardari to sign a regulation to introduce sharia, Islamic law, in Swat valley in order to pacify the Taliban.

Emboldened by the government's readiness to appease them, the Taliban moved into Buner from Swat more than a week ago, triggering alarm over their proximity to Islamabad.

The government and opposition have been reluctant to sanction the use of force in Swat, giving rise to doubts about the army's capacity and will to take on the Taliban.

"We will react if the writ of the government is challenged," Prime minister Yousaf Raza Gilani told parliament, challenging legislators to show "moral courage" to stop the Taliban.

Gilani also rebuffed concern that the militants posed a risk to the security of Pakistan's nuclear weapons. "The country's defense is in strong hands and our nuclear program is in safe hands," he said.

Losing ground

The military is confronted across the northwest by a Taliban menace that is now threatening to spread into Punjab province and the heart of the country.

On Thursday air force jets bombed militant targets in the Orakzai tribal region west of Peshawar.

Some 11 fighters were killed, taking the toll to 40 in three days of bombing, according to a military spokesman, though casualties cannot be independently verified.

Meanwhile, Taliban were also seen in another northwestern district of Shangla, manning checkpoints they had set up near Shahkot and Purn villages, according to intelligence officials.

Shangla, east of Swat and linked to Buner through a mountain pass, was the scene of fierce fighting between militants and security forces when the Pakistani military launched an offensive in late 2007 against militants loyal to Fazlullah.

The moves to defuse tensions in Buner came after intelligence officials in Peshawar briefed politicians from all the major parties in North West Frontier Province to build a consensus on how best to counter the Taliban threat.

The militants ambushed a convoy of Frontier Constabulary, as the government deployed more than 270 of the militiamen in Buner to restore the state's authority.

"There has been no other incident after the yesterday's firing on troops in which one policeman was killed," said Arsala Khan, a senior police official in Buner.

Taliban were entrenched in the mountains overlooking the town, according to Khan, but residents said Taliban fighters pray in their mosques and deliver sermons telling people to observe strict Islamic laws.

Residents of Buner saw a group of gun-toting fighters in an open<