Seven Afghan policemen have been killed by US forces in a "friendly fire" incident in the eastern province of Nangarhar, Afghan officials say.

The US military says US and Afghan forces retaliated after coming under fire. It did not confirm the deaths of the policemen.

Elsewhere Nato says its soldiers killed three civilians in Kunar province.

The International Committee for the Red Cross says the security situation in Afghanistan is deteriorating.

In a report marking 20 years of its work in Afghanistan, the ICRC said life for ordinary people in Afghanistan was getting worse.

"It's really had a heavy price in terms of the population, both in terms of wounded and in terms of killed and people displaced so it's a very worrying situation," the ICRC's director of operations, Pierre Kraehenbuhl, said.

'Brutal'

Local Afghan police insist that US-led forces opened fire on them first in the friendly fire incident at a security post in Nangarhar province on Monday night.