BAGHDAD, Iraq (AP) _ Iraq said U.S.-British warplanes killed six of its citizens in airstrikes Saturday on southern Iraq and that its air defense units hit one of the aircraft.

The U.S. military denied any aircraft was hit, saying all planes returned safely after a raid conducted in response to Iraqi anti-aircraft fire.

In a statement issued through the official Iraqi News Agency, the Iraqi military said allied aircraft attacked civilian targets in two districts in the southern province of al-Muthana, 220 miles south of Baghdad.

``Three people were martyred when enemy warplanes bombed southern Iraq and a residential house was destroyed in Salman and a farm was burned in Samawa,'' the statement said.

Later, the Iraqi military said the death toll had risen to six and that rescue workers were looking for more casualties while digging through the rubble of bombed houses.

The Information Ministry invited foreign journalists in Baghdad to go on an official trip to the sites on Sunday.

The U.S. Central Command in Tampa, Fla., said allied planes attacked Iraqi radar systems and anti-aircraft artillery, but its statement made no mention of civilian casualties.

``Coalition aircraft never target civilian populations or infrastructure,'' the command said. ``The sites were targeted to further degrade Iraq's ability to jeopardize coalition pilots and aircraft.''

The allied aircraft were fired on while patrolling the no-fly zone over southern Iraq, which was established after the 1991 Gulf War to protect Shiite Muslim rebels from Iraqi government forces.

Iraq does not recognize the no-fly zone and has been challenging allied aircraft since 1998.

``Our heroic (anti-aircraft) missile units confronted the enemy warplanes, hitting one of them while it was violating our skies,'' the Iraqi statement said.

The statement did not give the nationality of the plane or say that it fell to the ground. Iraq has previously claimed to have hit allied aircraft, but has never provided evidence.

The airstrike came hours before President George W. Bush's inauguration.