Insurgent fighters in a Taliban stronghold are being pounded by NATO forces and are on the verge of collapse, said the commander of Canadian forces in southern Afghanistan on Saturday.

Backed by U.S. and British air power, Canadian and Afghan troops took turns moving through former insurgent outposts in the Panjwaii region, where Taliban are engaging in a "last stand," according to Lt.-Col. Omer Lavoie

One U.S. soldier was killed Saturday in a rocket attack -- the first casualty alliance forces have suffered during Operation Medusa since four Canadians died last week and another was killed in a friend-fire incident.

NATO said 20 to 30 Taliban were killed Saturday, but the tally could not be independently confirmed.

Lavoie told The Canadian Press that advances by Canadian-led international troops from the north of the Taliban stronghold, along with a firm stand to the south, are punishing the insurgents.

"There's good indication that they are on the brink of collapse in a number of different areas," Lavoie said.

"Like most insurgents, they don't have the sustainment ability to have long, protracted engagements. What we see is mostly hit-and-run tactics."

NATO's commander in southern Afghanistan, meanwhile, said allied forces have no intention of allowing the Taliban to escape, despite reports from local officials of an escape route to the west.

"We've got the Taliban surrounded," said Canadian Brig.-Gen. David Fraser after a tour near the frontlines Saturday.

"We don't want to squeeze them out. We're around them, and they've got choices to make."

On Friday, Canadian foot soldiers were sent scrambling for cover under a bridge as rocket-propelled grenades flew past overhead and landed a short distance away, reports CP.

Small groups of Taliban fighters were testing the troops, triggering fiery exchanges and heavy bombardment.

"As you can tell, we are answering back with authority," said Lieut. Jeff Bell, a platoon commander with the Royal Canadian Regiment based in Petawawa, Ont., who was among the first wave of soldiers to move ahead.

Military officials are revealing little about the operation. Many details cannot be reported by The Canadian Press under the embedding agreement that allows reporters to accompany Canadian troops on the front lines.

More troops needed: general

A Canadian general, meanwhile, has told NATO chiefs that at least 2,000 more allied troops are needed to quell the Taliban insurgency.

Gen. Ray Henault, chairman of the NATO military committee, called Afghanistan the most complex mission NATO has ever undertaken.

He told NATO military chiefs in Poland that alliance forces in Afghanistan are meeting more resistance than anticipated. He said will appeal formally to the alliance's council on Monday for member nations to commit more troops.

Henault said so far, only 85 per cent of forces required for the mission have been supplied by the 26 member states.

With files from The Canadian Press and The Associated Press