Anbar province, where there was strong resistance to the US-led invasion, has been relatively quiet in recent months, partly because Sunni tribal leaders joined up with US-led forces to fight al-Qaeda.

The Ramadi bombing came just a few hours before a funeral march was held in Baghdad, the Iraqi capital, to mourn two traffic policemen who were killed in a battle with armed men a day earlier.

In the capital, dozens of mourners, including senior officials from the interior ministry, attended the funeral.

Fellow traffic police motorcyclists led the procession, which included the slain officers' wooden caskets wrapped in Iraqi flags.