June 2010 was the bloodiest month of the war with 102 killed as foreign forces pushed ahead with operations in southern Helmand and Kandahar provinces. Another 88 were killed in July.
There are currently more than 140,000 US and Nato-led troops in Afghanistan aiming to to flush out remnants of Taliban fighters, who went on the offensive after being toppled from government in the 2001 invasion.
Disputes over the Afghan war have already brought down a Dutch government in February and a German president in May.
The losses in Afghanistan are less than half of those in the Iraq war, where at least 4,723 foreign troops have been killed since 2003 - 4,405 of them Americans.
But, with the US government cutting troop numbers in Iraq before the formal end of combat operations on August 31, attention is certain to be focused back on the Afghan conflict.
Civilian casualties caused by US and other foreign forces have long been a source of friction between the Afghan government and its Western allies and led to a major falling-out between the two sides last year.
The UN report added that Taliban and armed groups were responsible for 76 per cent of casualties.
Deaths caused by "pro-government forces" fell to 12 per cent of the total from 30 per cent last year, due mainly to a 64 per cent fall in deaths caused by aerial attacks.