The army imposed a curfew in Miranshah, the main town in the semi-autonomous North Waziristan tribal region bordering Afghanistan, after seizing control of the bazaar and key government buildings, provincial authorities said.

Residents said more than 1,000 terrified families clutching belongings had fled the area following the fierce rocket and artillery clashes.

They were the most violent in the tribal belt since the fundamentalist Taliban regime in neighbouring Afghanistan fell in late 2001 and many fighters fled across the border.

"According to latest information, the death toll in March 4 (Saturday) fighting has gone up to 100. This is in addition to the 19 killed this morning in Miranshah," military spokesman Major General Shaukat Sultan told AFP.

Sultan had earlier said 19 militants, including some foreigners, died on Monday when troops tried to take control of a telephone exchange in Miranshah.

Five paramilitary soldiers were also killed on Saturday, he said. "We are establishing the government's writ," he said.

The fighting erupted on Saturday when hundreds of tribal rebels seized government buildings in revenge for an army raid three days earlier targeting an Al-Qaeda training camp. That raid was said to have killed 40 militants, including foreigners.