Afghanistan , October 26 2009 : In the first incident, four US soldiers died and two were hurt when two helicopters collided mid-air in the south, Nato-led forces said.

In a separate incident seven soldiers and three civilians were killed in a helicopter crash in the west.

Hostile fire was ruled out as a cause of the collision but no cause has yet been identified for the crash.

Twelve Americans and 14 Afghans were injured in that incident.

This year has seen the highest death toll of international troops in Afghanistan since the Taliban were overthrown in 2001.

There have been dozens of American soldiers among those killed.