The death toll, up 39 percent from the same period in 2007, includes 800 killings blamed on Taliban and other militants as well as 577 caused by Afghan forces and their US-led coalition allies. Responsibility for another 68 deaths was not clear.

There were 330 civilians killed in Afghanistan in August alone, spokesman Rupert Colville said.

Air strikes by international forces caused nearly 400 civilian deaths in the year through August, the UN office said, calling for accountability and greater transparency about those attacks.

The Taliban carried out 142 summary executions and also used suicide attacks and improvised explosive devices, according to the report drawn up by human rights officers attached to the UN Assistance Mission in Afghanistan.