31 U.S. troops killed in crash

A US helicopter crash in eastern Afghanistan has killed 31 US Special Forces and seven Afghan soldiers.



Afghan President Hamid Karzai's office says many of those killed were from the elite Navy Seals.



Neither the US nor the North Atlantic Treaty Organisation- Nato have confirmed the cause, but witnesses, officials and the Taliban say it was shot down overnight in Wardak province.



The incident is believed to be the biggest single loss of life for US forces in Afghanistan since operations began in 2001.



The helicopter was reportedly returning from an operation against the Taliban in which eight insurgents are believed to have been killed.