NATO-led forces in Afghanistan said on Wednesday they killed eight young Afghans in eastern Kapisa province last week in an air strike that enraged the Afghan government, and came soon after a United Nations report showed civilian casualties of the decade-long war rose again in 2011.

"Eight young Afghans lost their lives as the result of an air strike by coalition forces," General Lewis Boone, communications director of the International Security Assistance Force (ISAF) coalition, told reporters.

The victims appeared to be carrying weapons and were walking in a menacing manner, prompting ISAF forces in the area to request air support, he said.

"The aircraft dropped two bombs on the group that we believed to be an imminent threat to our people ... in the end, eight young Afghans lost their lives in this very sad event."

Afghanistan's Hamid Karzai, whose support is undermined by civilian deaths, has repeatedly urged NATO forces to stop killing villagers..

Afghan government officials this week showed gruesome photographs of eight dead boys from what they said was the Kapisa bombing, and said seven of them had been aged between six and 14, while one had been around 18 years old. They were bombed twice while herding sheep in heavy snow and lighting a fire to keep warm, they said.

The U.N. said this month the number of civilians killed and wounded in the Afghan war rose for the fifth year in a row, to 3,021 in 2011 from 2,790 in 2010.

Reuters