Military officials are probing two clashes in which Afghan civilians and police may have been killed by U.S.-led coalition forces, authorities said Monday.

The U.S. military has begun an inquiry into Saturday's deaths of seven Afghan civilians after American forces using aircraft and artillery battled militants in a house and a cave complex in Afghanistan's Kunar province, which borders Pakistan.

The Canadian-led military in the southern Kandahar province also said it was investigating whether "friendly fire" was responsible for casualties sustained by Afghan police during fierce fighting there Friday against Taliban forces.

Afghan authorities said 41 Taliban militants and six Afghan police were killed during the fighting in Sangisar, a former Taliban stronghold near Kandahar city. It was the bloodiest battle in a surge in rebel attacks that threatens the government's shaky grip on the country more than four years after the fall of the Taliban.

The government has previously complained about heavy-handed tactics by U.S.-led forces, and the swift announcement of probes into the deaths appears to reflect greater openness on the part of the coalition, which says its forces go to extreme lengths to avoid innocent casualties.

Saturday's clash in Kunar province came during an ongoing operation involving 2,500 Afghan and coalition forces to flush out Taliban-led militants, one of the biggest offensives since the Taliban's ouster for hosting Usama bin Laden.

The U.S. military said about eight to 10 militants opened fire on U.S. forces, who returned fire and called in support from warplanes and artillery. It said several Taliban forces were killed and others took shelter in a house and nearby cave where civilians were living.

U.S. military spokesman Maj. Matt Hackathorn said they stopped firing once they realized civilians were in the area. After the firefight ended, local village elders said seven people had been killed and three wounded.

"Whether our direct fire was responsible (for the casualties) or close-air support or if the victims were caught in the crossfire we just don't know right now," he said. "We are profoundly sorry about the loss of life."

Maj. Gen. Benjamin C. Freakley, coalition commander, has ordered an investigation.

On the Pakistani side of the border, troops deployed to block any Taliban militants fleeing the Kunar offensive into Pakistan, a Pakistani army official said on condition of anonymity because he wasn't authorized to speak to the media.

Coalition forces have also opened an investigation into Friday's battle near Sangisar, where up to 60 Taliban members had been hiding.

Afghan soldiers and police, backed by Canadian forces and coalition gunships, attacked the rebels after learning that they were planning to raid Kandahar city. A coalition statement said that during the fighting, Afghan police "reported casualties, some possibly caused by friendly forces."

"We are investigating the incident and we will work jointly with the government of Afghanistan to determine the events that took place during this fight," said Canadian Brig. Gen. David Fraser.

Separately, Authorities have banned unregistered motorcycles in the central Afghan province of Ghazni because Taliban militants use bikes to carry out bombings and shootings. Gunmen on motorcycles killed a former governor last month.

Police said militants have also been using motorcycles when planting roadside bombs or in suicide attacks.

Taliban militants responded by warning villagers against going to the capital of the province, about 75 miles southwest of the capital Kabul, said Ali Ahmed, director of the province's criminal department.