An investigation has begun on whether a Nato air raid was to blame for the death of Afghan soldiers and foreign troops during a joint operation in the northwest of Afghanistan.

Nato's International Security Assistance Force (Isaf) said the attack on Friday killed or injured more than 25 foreign and Afghan soldiers in the province of Badghis.

Nato officials blamed Taliban fighters for the attack, but later said it was possible that the soldiers were hit by a Nato-led air raid.

Mohammad Zahir Azimi, the spokesman for Afghanistan's defence ministry, told the AFP news agency there was no doubt Afghan personnel had been killed and injured by their international partners.

"It was an erroneous air strike which caused casualties to friendly forces," he said.

The troops had apparently called in air support after they became involved in a battle with Taliban fighters while searching for two missing US paratroopers from the 82nd Airborne Division.

It was not immediately clear how many of the casualties were Afghan and how many from the international forces.

Fate in the balance

Afghan officials earlier said the two missing paratroopers had drowned while trying to recover airdropped food packages from a river.

The Taliban said that international forces had played down the actual toll from the air raid.

"There was ... a firefight between Taliban and Afghan and foreign forces in Murghab district of Badghis province. The fighting lasted for hours and was very intense, at a close distance," Qari Yusuf Ahmadi, a Taliban spokesman, said.

"By the end of the day, foreign forces bombed the area where the clash was going on and due to their own bombing, 32 foreign and 43 Afghan soldiers were killed."

Badghis is one of several provinces in the previously quiet west and north of Afghanistan, where Taliban activity has increased dramatically in recent months.