Five American soldiers are dead after a UH-60 Black Hawk military helicopter crashed in Afghanistan on Monday.

Taliban fighters sought to take credit for the crash in Daman, near Kandahar, but this was disputed by the NATO-led International Security Assistance Force (ISAF) and the accident has since been attributed to heavy rainfall.

The ISAF said in a statement: "The cause of the crash is under investigation. However, initial reporting indicates there was no enemy activity in the area at the time."

Police chief general Abdul Razeq told AFP: "There was bad weather in the area and the helicopter crashed at around 10pm. No insurgents were there at the time."

It has been confirmed that everyone on board the helicopter perished in the crash.

The night-time crash came just hours after two US soldiers were killed and 10 more injured when an Afghan Army soldier reportedly turned his weapon on his allies. The suspected insider attack happened in the eastern province of Wardak.

The two incidents made 11 March the costliest day of the year thus far for United States forces in Afghanistan. In fact it is the bloodiest day since last August, when seven Americans and four Afghans were killed in another Black Hawk crash in Kandahar.

Twelve American soldiers have now been killed in Afghanistan thus far this year. Last year 297 US troops died in the country.

Just days ago, Afghan President Hamid Karzai accused the US of colluding with Taliban bombers to convince his country's population that foreign troops are indispensible.