Prime Minister Stephen Harper described a coalition air attack in Afghanistan that killed a number of civilians as an "unfortunate accident."

"These are difficult circumstances. The Taliban does mix in with the civilian population and these are real problems," he said.

Commenting after a speech Wednesday to a business audience in London, Ont., Harper admitted it wouldn't help the efforts of Canada or other coalition countries to help build peace.

Harper said he had no reason to believe Canadian troops were involved in the attack because Canadian troops aren't involved in air missions.

The Taliban must be dealt with as coalition forces rebuild the country, he said.

Coalition forces engaged about 200 Taliban fighters near the village of Azizi, about 35 kilometres west of Kandahar, on Sunday.

Late Sunday or early Monday, the fighters retreated into the village, but continued fighting coalition troops. They took refuge in homes and a religious school.

Someone ordered air strikes.

At least 16 villagers were killed, but some estimates put the death toll at 25 or higher.

The U.S. military confirmed the death of at least 20 militants but believes they may have killed up to 60 insurgents.

The area has been closed to journalists.

Outside the building where Harper spoke, about two dozen protestors called for the return of Canadian troops from the war-torn country.

"We have no business being there," Stephen Maynard, 23, a student at the nearby University of Western Ontario, told The Canadian Press.

"The smoke and mirrors being put up by this administration is one of the reasons I'm here, to tell Mr. Harper that his tact and the way of going about solving world problems just isn't the right way to do it."

However, Harper said that pulling troops from Afghanistan would cause chaos, and would be nothing short of abandoning the Afghan people.

"If Canada pulls out, it results not just in a humanitarian catastrophe, but in a vicious and brutal dictatorship that we had before under the Taliban that nobody in that country wants to go back to," he said.

Afghanistan's President Hamid Karzai has condemned both the civilian deaths and the Taliban's use of civilian homes as shelter. He has ordered an investigation.

"The ultimate cause of why civilians were injured and killed is because the Taliban knowingly, willfully chose to occupy homes of these people," Col. Tom Collins, a U.S. military spokesman, told reporters in Kabul on Wednesday.

"We do everything we can to prevent killing civilians." However, he said coalition troops

Human rights groups condemned both the military and the Taliban.

"Taliban insurgent forces who take shelter in a civilian area knowing that it's going to draw hostile fire are violating international law," said Sam Zarifi, head of New York-based Human Rights Watch's Asia division.

Other news

About 60 Taliban and four Afghan soldiers died Tuesday night during fighting in southern Afghanistan.

The fighting occurred in the Tirin Kot district of Uruzgan province, just north of Kandahar province where Canadian troops are operating.

Uruzgan has seen some of the heaviest fighting in Afghanistan.

The violence has intensified in recent weeks, and Collins said the Taliban have grown in "strength and influence" recently in the southern and eastern areas of Kandahar, Helmand and Uruzgan.

With files from The Canadian Press