PESHAWAR, Pakistan (AFP) - – Pakistani helicopter gunships and ground troops pounded Taliban fighters on Friday, killing up to 60 militants and destroying a dozen would-be suicide bombers in fierce fighting, the army said.

The military launched the gruelling assault in the northwest of the nuclear power six days ago under US pressure after the Islamist hardliners advanced to within 100 kilometres (60 miles) of the capital Islamabad.

As the fighting raged, US Defence Secretary Robert Gates appealed to Congress to free up money for military aid to Pakistan, which is central to Washington's strategy for stopping the insurgency in neighbouring Afghanistan.

"During the last 24 hours, 55 to 60 militants have been killed," Major General Athar Abbas told a briefing update on the operation in Buner district.

Based on combined tolls released by the military, nearly 200 militants have been killed in Operation Black Thunder since tanks, fighter jets and helicopter gunships swung into action in Buner and neighbouring Lower Dir.

None of the deaths or details provided by the military could be immediately confirmed independently.

Abbas described "fierce fighting" in the northern area of a strategic pass that heads towards Islamabad and said that 400 "well-equipped and organised" Taliban were putting up "stiff resistance" in Buner.

Ground troops backed by helicopter gunships destroyed nine suicide vehicles and six vehicles of "fleeing militants," he said. Three "suicide motorcyclists" were shot dead by ground troops advancing on narrow mountain tracks, he said.

A suicide bomber blew up a booby-trapped house killing two paramilitary soldiers and wounding eight others, said Abbas, bringing the military's overall losses to 13 during the offensive.

Another suicide bomber was arrested after detonating his explosives and wounding himself, the spokesman said.

The Pakistani government ceded control of the nearby Swat valley in February, signing a deal to allow religious hardliners to enforce Islamic law in the region in order to end a bloody two-year rebellion led by a radical cleric.
But instead of disarming as required under the deal, the Taliban instead pushed further south towards Islamabad, taking over large swathes of Lower Dir and Buner -- and prompting the latest army offensive.
The military accused militants of violating the peace agreement by erecting multiple checkpoints, planting hundreds of improvised bombs, abducting government employees and beheading four other people in Swat.
People living in Buner said Friday that the fighting was heavy.
Hazrat Khan, 26, a teacher in Sultanwas, said he, his wife and four children had been holed up at home for four days, with food running low.
"I can see through chinks in the door that Taliban are everywhere out there. I can't move because of the curfew and shelling," he said.
On Friday, more than 50 armed Taliban stormed a local paramilitary headquarters in Upper Dir -- a district so far shielded from the offensive -- and snatched then released 10 security forces personnel, officials said.
Taliban fighters have kidnapped scores of security personnel in their increasingly brazen insurgency inside Pakistan, where US counter-terrorism experts say nearly 2,300 people were killed in militant attacks last year.
The military said the house of a local commander was destroyed at Pir Baba and that "reportedly a few foreign militants" were killed.
Authorities said Friday they rejected a request from a pro-Taliban cleric, Sufi Mohammad who negotiated the February deal, to halt the offensive unless militants laid down their arms, after talks between the two camps resumed.
The militant campaign has proved to be a serious challenge for the government of President Asif Ali Zardari, who pledged this week not to let the country's nuclear weapons arsenal fall into the hands of militants.
The United States says Al-Qaeda, Taliban and other militants who have found a relative safe haven in Pakistan are the biggest terror threat to the West.
Dozens of missile strikes from suspected unmanned US planes have targeted militants in Pakistan's northwest border area with Afghanistan, in attacks Pakistan publicly says are a violation of its sovereignty.
Gates, the US defence secretary, said Washington would start running out of money to give Pakistan military assistance in mid-May unless Congress quickly approved releasing more aid.