Iraq threw open the world's third largest oil reserves to foreign firms yesterday, putting British and US companies in poll position five years after US-led troops invaded the country to oust Saddam Hussein.

The move to invite bids for the development of Iraq's largest oilfields will mark the return of the oil majors, whose cash and technical expertise Iraq needs to restore its oil infrastructure that has been hard hit by sanctions and war.

But any awards to US and British firms are likely to anger opponents of the invasion, who have said the 2003 war was designed to give Western oil companies control over Iraqi oil reserves. US and British officials have denied the charges.