(Updates with more detail throughout)

BAGHDAD, Jan 10 (Reuters) - U.S. warplanes dropped 40,000 pounds of bombs on more than 40 targets on Baghdad's southern outskirts on Thursday in a major strike on al Qaeda safe havens, the military said in a statement.

The U.S. Air Force dispatched two B-1 bombers and four F-16 fighter jets, aiming at three large target areas in Arab Jabour, an area of date palm groves that has become a haven for al Qaeda fighters driven out of other areas.

The attack was described as part of Operation Phantom Phoenix, a countrywide offensive against al Qaeda guerrillas that U.S. forces launched this week.

Air strikes on such a large scale have been rare in Iraq, especially over the past few months when the intensity of military action tapered off as overall violence declined.

Operation Phantom Phoenix has so far also included a large-scale sweep in Diyala province north of Baghdad by thousands of U.S. and Iraqi troops. Six American soldiers were killed on Wednesday by an explosion in a booby-trapped house.

(Reporting by Peter Graff; editing by Ross Colvin)

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