U.S.-backed coalition forces in Afghanistan are investigating two cases in which civilians and Afghan security forces may have been killed by friendly fire during combat operations targeting Taleban insurgents.

U.S. military officials say they are taking both cases extremely seriously and have separate investigations to determine what happened.

In one case, at least seven Afghan civilians were killed Saturday during a coalition-led offensive in eastern Afghanistan.

U.S. spokeswoman Lieutenant Tamara Lawrence says coalition aircraft and artillery targeted suspected Taleban hideouts in Kunar province.

"Several of the insurgents are believed to have been killed, the rest retreated," said Lawrence. "Coalition forces rushed three wounded civilians to the provincial team site for emergency treatment and are working with Afghan government officials to return the remains of the other civilians to their families."

The American commander in charge of the operation, Colonel John Nicholson, said he "sincerely and profoundly regretted the loss of innocent life."

The fighting occurred during the recently launched Operation Mountain Lion, one of the largest operations in the country since the U.S.-led coalition ousted the Taleban in 2001.

Also Monday, coalition authorities announced a separate probe into Friday's assault on Taleban militants in southern Afghanistan.

Local police say they suffered a number of casualties during the attack from coalition fire. Afghan officials say that at least six policemen died along with more than 40 insurgents during the attack. The gun-battle was one of the fiercest in months and coincides with a sharp rise in insurgent activity in Afghanistan.

The Canadian authorities - now leading coalition forces in the southern part of the country - say they are looking into the case and reviewing combat procedures.

Troop commanders insist they are now taking every possible precaution to avoid civilian casualties.