Updated

Security forces clashed with militants across Pakistan's wild tribal belt Wednesday, killing as many as 49 insurgents, the army said, a week after U.S. ally Pervez Musharraf resigned as president.

In the most serious incident, troops rained fire from guns and artillery on militants holed up in a health center in the Bajur region, killing 30 and wounding many more, said military spokesman Maj. Murad Khan.

Security forces assessed the toll with the help of intercepted radio traffic among the insurgents, he said, but spokesmen for the militants could not be reached to confirm the report.

Musharraf, a close ally in the U.S.-led ‘war on terror,’ quit rather than face the humiliation of impeachment, triggering a scramble for power that resulted in the collapse of the country's ruling coalition earlier this week.

Lawmakers are expected to elect Asif Ali Zardari, the widower of slain former leader Benazir Bhutto, as his successor on Sept. 6. His party, which controls the largest bloc in Parliament, has already started toughening its stance against militants.

Troops are engaged in bloody offensives against Islamic extremists in the northern Swat valley and in Bajur, a region considered a launchpad for Taliban operations into neighboring Afghanistan and a possible hideaway for Al Qaeda chief Osama bin Laden.

Officials say hundreds of militants have died in the weeks-old operation, while residents say civilians have also been killed in incidents including mortar strikes on their homes.

An estimated 200,000 people have fled to safer areas.

Police said eight militants died and 10 were wounded when government forces fired on suspect vehicles in two areas of Bajur early Wednesday, though the reported casualties could not be verified independently.

In a sign that a third front in the struggle may be opening up, the military said between 75 and 100 militants assailed a military fort in the South Waziristan region at about midnight Tuesday.

Troops guarding Tiarza Fort and a checkpoint on a nearby bridge "responded effectively and repulsed the attack," a military statement said, adding that 11 militants died and up to 20 were wounded.

It made no mention of any casualties among the troops.

Suspected militant hideouts in South Waziristan have been targeted in a stream of suspected U.S. missile attacks, including one that killed a senior Al Qaeda commander in July.

Aminullah Wazir, a shopkeeper in Wana, the region's main town, said security forces imposed a curfew in the area Wednesday. Shops were shut and the streets deserted, he said.

"We heard shelling and gunfire almost all night," Wazir told The Associated Press by telephone.

Pakistan's 5-month-old government initially dabbled in peace talks with militants. But the initiatives have borne little fruit, and U.S. officials have been pressing for stiffer action against insurgents they blame for soaring violence in Afghanistan.

Pakistan this week banned the local wing of the Taliban movement after it claimed responsibility for a double suicide bombing that killed 67 people at an arms factory near the capital.

On Tuesday, gunmen fired at the car of a senior U.S. diplomat in the northwestern city of Peshawar and a bomb killed seven at a roadside restaurant near Islamabad.

Pakistanis and the country's Western backers worry that the political turmoil since Musharraf's ouster after nine years in power could distract efforts to deal with the many challenges ahead, including shoring up the flagging economy.

On Wednesday, the Karachi stock exchange's benchmark 100-share index fell another 3 percent. The index has plummeted by more than 40 percent since April and stands at its lowest level in more than two years.