Al-Qaida in Iraq has claimed responsibility for an attack in northwestern Tal Afar, where a female suicide bomber killed five people and wounded 30 others

The U.S. military said the attack was outside a compensation center for civilians who have lost relatives or property because of U.S. military action.

Earlier, Iraqi police said the attack was at an army recruiting center.

Meanwhile, an explosion near the home of a bodyguard for radical Shi'ite cleric Moqtada al-Sadr killed at least two people in the city of Najaf. 

In Washington, President Bush warned that terrorists in Iraq may seek to increase violence in an effort to disrupt a constitutional referendum next month.

A recent poll by U.S.-based think tank International Republican Institute shows that 85 percent of Iraqis expect to vote in the referendum.

Some information for this report provided by Ap, Reuters.