Afghan and U.S. troops surrounded a Taliban stronghold Thursday, where two leaders of the rebellion in southern Afghanistan are thought to be hiding.

• INDEPTH: Afghanistan

The operation occurred as the number of insurgents killed in a three-day assault in the region rose to 102, according to a government official.

Soldiers believe they may have two Taliban commanders, Mullah Dadullah and Mullah Brader, in their sights. The pair is accused of organizing attacks across much of the country's violence-ridden south.

The Taliban is facing one of the biggest assaults by the U.S.-led coalition and Afghan forces since the fall of its regime in 2001.

An Afghan Defence Ministry spokesman said Thursday that many of the Taliban's dead are still lying out in the open.

Dozens killed in Kandahar fighting

As many as 12 Afghan policemen and soldiers also died during 11 hours of fighting on Tuesday that left bodies scattered across the hills in northern Kandahar province.

The U.S. military put the insurgent death toll in Tuesday's fighting at 49, but Kandahar police said they had recovered the bodies of 76 militants from the battlefield along the border with Zabul province.

Kandahar's deputy police chief, Gen. Salim Khan, said 30 more militants had been captured.

The battle was part of an operation to destroy militant hideouts and weaken the insurgency before a parliamentary election set for September, the U.S. military said.

U.S. helicopters and attack planes pounded the hills about 400 kilometres southwest of Kabul, said a U.S. military spokesman, Lt.-Col. Jerry O'Hara.

"This is an ongoing effort to take away enemy sanctuaries," he said in a statement. "We are not letting up on the enemy and will continue to pursue them until the fighting stops."