Key Points:

The United States military yesterday said it was investigating claims an operation killed two dozen Afghan civilians.

Afghan officials said a government inquiry found only militants were killed in the Tuesday raid in the Tagab Valley, a region just 50km north of the Afghan capital, Kabul where insurgents have a strong presence.

Afghan news agency Pajhwok quoted villagers as saying 25 civilians died in the raid. The US announcement came a day after President Hamid Karzai made his latest plea to US and Nato troops to avoid killing civilians.

Civilian deaths could undermine Karzai's re-election bid this year, and such killings also erode the support that the foreign forces need to help his Government extend its reach.