KABUL: The Afghan Defense Ministry has condemned the killing of four Afghan soldiers in a NATO airstrike.

A statement confirms that a joint NATO-Afghan force clashed with another Afghan unit about 3 a.m. on Saturday in eastern Wardak province.

It says NATO forces requested air support and four Afghan soldiers were killed in the strike.

The Defense Ministry says it is condemning the incident and wants those responsible to be brought to justice after an investigation.

The NATO official said earlier only two Afghan soldiers were killed, but it was not immediately clear who fired on them.

The fighting reflects the difficulty facing foreign troops as they increasingly partner with Afghan forces with a heightened emphasis on training and an influx of 37,000 more U.S. and allied troops.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

KABUL (AP) — NATO troops clashed with Afghan soldiers and called in air support Saturday in fighting that left as many as four Afghan troops dead, officials said.

A NATO official said a gunbattle broke out when a joint force came under fire in the Wardak province, south of the capital Kabul, in what may have been a friendly fire incident.

Wardak provincial spokesman Shahidullah Shahid said NATO and Afghan soldiers began fighting each other at about 3:30 a.m. after a "misunderstanding" following an operation in the Sayed Abad district.

Shahid said four Afghan soldiers were killed and seven wounded.

The NATO official said only two Afghan soldiers were killed, but it was not immediately clear who fired on them.

The official, who spoke on condition of anonymity to release the information ahead of an official announcement, said an investigation was under way.

The conflicting casualty tolls could not immediately be reconciled. The Afghan Defense Ministry also said it was investigating.

The confusion reflects the difficulty facing foreign troops as they increasingly partner with Afghan forces with a heightened emphasis on training and an influx of 37,000 more U.S. and allied troops.

NATO forces also killed two civilians after opening fire on a taxi as it sped toward a patrol and ignored warnings to stop Friday in the Gelan district of Ghazni province, the international force said.

Elsewhere, joint NATO-Afghan forces came under attack in the northwestern province of Badghis at about 1 a.m. Saturday, prompting a gunbattle and an airstrike that killed eight militants, including a group leader, deputy provincial police chief Abdul Jabar Khan said.