This article is more than 11 years old

This article is more than 11 years old

Taliban fighters spilling out of the Swat Valley have swept across Buner, a district 60 miles from Islamabad, as Hillary Clinton warned the situation in Pakistan now poses a "mortal threat" to the security of the world.

The US secretary of state told Congress yesterday that Pakistan faced an "existential" threat from Islamist militants. "I think the Pakistani government is basically abdicating to the Taliban and the extremists," she said. Any further deterioration in the situation "poses a mortal threat to the security and safety of our country and the world", she said.

In Buner, Taliban fighters occupied government buildings, ransacked the offices of aid agencies and ordered aid employees to leave. Fighters brandishing guns and rocket launchers patrolled villages, forcing beleaguered local police to retreat to their stations. Local courts have stopped functioning and judicial officials have gone on indefinite leave.

This morning the provincial government said it was deploying six platoons of paramilitaries – between 180 and 300 troops – to retrieve control of the government installations.

The turmoil in Buner, a district of about 1 million people, does not pose an immediate threat to Islamabad, which lies across a mountain range and the river Indus. But the speed and aggression of the militant advance has stoked a sense of alarm across the country, even among normally conservative forces.

"If Taliban continue to move at this pace they will soon be knocking at the doors of Islamabad," Maulana Fazlur Rehman, leader of the pro-Taliban Jamiat Ulema e Islam party, told the national assembly yesterday.

The Taliban could soon seize control of Tarbela Dam, a strategic reservoir, Rehman warned.

Blame for the turmoil has focused on a controversial peace deal the provincial government signed with militants in February. Hoping to defuse the insurgency, the Awami National party-led government acceded to demands for sharia law in Swat and seven surrounding districts, known collectively as Malakand Division.

The changes were ratified by the national parliament last week with cross-party consensus. Since then, the Taliban have moved to establish much more than judicial control.

In Mingora, the commercial hub of Swat, the police retain a low-key presence, reduced to directing traffic. Most politicians have fled, many under death threats. Many residents said it was not clear who was in control of the town.

In Imam Dheri, the Taliban headquarters near Mingora, a Taliban spokesman, Muslim Khan, told the Guardian their goal was the establishment of an Islamic caliphate first in Pakistan and then across the Muslim world.

"Democracy is a system for European countries. It is not for Muslims," he said. "This is not just about justice. It should be in education, health, economics. Everything should be under sharia."

The drive into Buner signals the next step in that strategy. Khan said Taliban fighters were being deployed to ensure sharia law was implemented there too.

They are also muscling in on other areas. On Wednesday, militants kidnapped a senior government official in Upper Dir, west of Swat, for a few hours before releasing him.

Defending the government, Pakistan's ambassador to the US, Hussain Haqqani, said Islamabad was pushing for a negotiated peace just as the US had done with Iraqi militants.

"To think that that strategy somehow represents an abdication of our responsibility towards our people and towards the security of our country and the region is incorrect," he told CNN.