At least 10 British military personnel were believed to have been killed on Sunday when a Royal Air Force transport plane they were abroad crashed in northwest of Baghdad, the British Press Association reported.

The figure of those killed was around "10", with it "highly unlikely" to be more than 15, the news agency quoted military sources as reporting.

British Sky TV earlier quoted military sources as reporting that up to 15 British military personnel could have been killed in the crash.

The British Ministry of Defense confirmed earlier in the day that a C-130 Hercules crashed at around 17:25 local time (1425 GMT)some 30 km northwest of the Iraqi capital.

However, it could not provide details on the cause of the crashand the extent of causalities among personnel on board.

If the casualties are confirmed, it would be the biggest loss of life for British forces since they joined the US-led war against Iraq in March, 2003.

According to the British military, 76 service personnel have been killed in Iraq since the start of the Iraq war.