Up to 15 British troops were killed when a transport plane crashed near Baghdad in what could be Britain?s biggest single loss of life in the Iraq campaign, a military source says. Prime Minister Tony Blair said a number of Britons died when the C-130 Hercules transport plane crashed on Sunday. He gave no figure but the source said about 10 were dead and it could rise to 15.

?We are investigating and our thoughts are with the families of those who were on board the plane,? the source said. There was no comment on the cause of the crash or whether the plane had been shot down. US officials said helicopters had spotted wreckage strewn over a wide area. ?Yet again today we see the sacrifice they make,? Blair said in a statement on Sunday?s Iraqi election.

?Our thoughts and prayers are with the families of those who lost their lives earlier today. They can be so proud of what their loved ones accomplished. This country and the wider world will never forget them.? The plane crashed at around 5:25 p.m. (2.25 p.m. British time) some 20 miles northwest of Baghdad, the Defence Ministry said in a statement. It was on its way from Baghdad to Balad, a major US military air transport hub, when it crashed.

It was not clear why there was still doubt about the casualty toll, although darkness would have hampered any search of the wreckage. Military transport flights around Iraq often pick up personnel at short notice if they have space available. Before Sunday?s accident, 29 British troops had been killed in combat in Iraq and 43 more had died in non-combat incidents.

Eight died when a US helicopter crashed in the Kuwaiti desert on the eve of the US-led invasion in March 2003. On two occasions, six British troops have been killed in incidents. British, US and other foreign troops were helping Iraqi forces provide security for the election. Insurgents had threatened to kill anyone who tried to vote and there were at least nine suicide bomb attacks in Baghdad. On Wednesday, 31 US troops were killed in a helicopter crash, the deadliest single incident for Americans in Iraq.