BAGHDAD - Local residents say Iraqi soldiers for the first time have warned residents in embattled Sadr City district to leave their houses for security reasons.

They say the soldiers, using loudspeakers, told residents to go to nearby soccer stadiums. But most residents still have not fled the neighbourhood. Thursday's warning signals that U.S.-backed forces are preparing to launch a new push into the area to clear pockets of Shiite extremists who have been battling U.S. soldiers for almost seven weeks.

UNICEF has said about 6,000 people have been forced to flee their homes in the Shiite militia stronghold and that some areas of southeastern Sadr City were virtually abandoned.