Six British and one American soldier were killed in a midair collision between two British Royal Navy helicopters over international waters in the Gulf on Saturday.

The total number of casualties among the coalition forces during the ongoing Iraq offensive has now gone up to 20.

The United Kingdom central command in Doha said the collision was an accident and that the Royal Navy had ordered a probe into the cause.

The two Sea King Airborne Early Warning Aircraft collided and crashed eight kilometres from the Royal Navy's flagship.

The helicopters were not struck by enemy fire, a spokesman for British forces in the Gulf was quoted as saying.

The helicopters crashed about 4:30 am [0700 IST], soon after take-off from a ship in the Gulf, officials said.

Pentagon has confirmed that a US Navy officer was among the victims.

PTI