The U.S. military and Afghan forces have launched an investigation into civilian deaths that occurred earlier this week in a battle between the U.S.-led coalition and Taliban fighters in southern Afghanistan.

In a statement released late Thursday, the U.S. military confirmed that there were civilian deaths when U.S. and Afghan forces fought with the Taliban in the Sangin district of Helmand province on Tuesday, but it did not say how many.

The governor of Helmand province said at least 21 civilians died when the U.S.-led coalition launched air strikes against Taliban fighters who had sought shelter in the homes of villagers about 25 kilometres north of the town of Sangin.

A resident of the area put the civilian death toll closer to 40.

The U.S. military said it had treated 20 Afghan civilians injured in the battle, which lasted 16 hours. It said one of the injured was a child who later died.

"There are confirmed reports of civilian casualties" but the number was not certain, the statement said.

"A joint Afghan and coalition force inquiry is being conducted."

The U.S. military said about 200 Taliban fighters were involved in the battle and a significant number were killed.

Tuesday's battle in Sangin is the third major incident involving civilian deaths in Afghanistan in fighting between U.S. and Afghan forces and Taliban fighters in the past three months.

In March, 19 civilians were killed in eastern Afghanistan after U.S. Marines opened fire on civilians in the wake of a suicide attack. Fifty more were wounded.

In April, about 50 civilians were killed in western Afghanistan because of a combination of air strikes and fighting, according to Afghan and UN officials.

Anger is rising in Afghanistan over civilian casualties at the hands of international forces.

On Tuesday, Afghanistan's upper house of parliament passed a bill calling for talks with the Taliban to end the ongoing conflict. The bill also calls for an end to international military operations against the Taliban when efforts to begin such talks get going.

Canada has more than 2,000 soldiers stationed in Afghanistan, the majority in the southern province of Kandahar.

Fifty-four Canadian soldiers and one diplomat have been killed since Canada first sent troops to the troubled country in early 2002.

With files from the Associated Press