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 Defence 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.

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