Kabul - US-led coalition forces mistakenly bombed an Afghan national army position in Khost province early Wednesday and killed at least nine soldiers, while more than 40 militants and three police were killed elsewhere in the country, officials said.

The airstrike occurred in Sayedkhail district of the south-eastern province of Khost when a coalition convoy was returning from an operation, the US military said in a statement.

"Initial reports from troops on the ground indicate that this may be a case of mistaken identity on both sides," the statement said.

"At 2 am today during a bombardment of international forces, nine Afghan army soldiers were killed and three were wounded," the Afghan defence ministry said in a statement, adding that one of the wounded soldiers was in critical condition.

Coalition forces were coordinating with the Afghan government for a joint investigation into the incident, the US military statement said.

Afghan defence ministry condemned the attack and vowed to bring the perpetrators to justice.

"The national defence ministry condemns the attack in the strongest terms," the statement said, adding, "We promise to Afghan people and national army personnel to follow the incident strictly so that the perpetrators of this action (will) be prosecuted and brought to justice under applied laws."

The friendly-fire incident could strain relations between the coalition troops and Afghan army forces, who are fighting the Taliban-led insurgency in the country. Around 
70,000 international troops are stationed in Afghanistan.

In a separate incident, more than 150 Taliban militants attacked Deh Rawood district headquarters in southern Uruzgan province on Tuesday night, sparking a fierce battle with Afghan police forces, Juma Gul Hemat, provincial police chief, said.

"Reinforcement was sent to the area and in the firefight that continued until 4 am today, more than 35 Taliban militants were killed," Hemat told Deutsche Presse-Agentur dpa by phone from the area.

Three policemen were killed and six others were wounded in the battle, he said, adding that the rest of the militants fled the area when NATO gunship helicopters arrived at the scene.

He said 40 weapons were recovered from the militants, whose bodies were still at the site.

In the Nad Ali district of southern Helmand province Tuesday, Afghan army troops backed by coalition airstrikes killed or wounded an unspecified number of rebels, the defence ministry claimed.

The bodies of "five known Taliban members" were among those killed and recovered by the soldiers, the army statement said.

US military also said coalition troops along with Afghan forces killed seven Taliban militants including one of their leaders in separate clashes in southern and eastern Afghanistan on Tuesday.

Due to the remoteness of the area, it was difficult to verify the Taliban death tolls independently.

More than 4,000 people, mainly insurgents, have been killed in violence so far this year. (dpa)