The Iraqi government says its forces have arrested the leader of al-Qaida in Iraq.

An Interior Ministry spokesman, Major General Abdul Karim Khalaf, told Iraqi state television Thursday that Iraqi forces had captured Abu Ayyub al-Masri during a raid in the northern city of Mosul. He said al-Masri had identified himself to police using his alias, Abu Hamza al-Muhajir.

Both the Iraqi government and the U.S. military say they continue to investigate the matter.

Al-Masri took over command of al-Qaida in Iraq from Abu Musab al-Zarqawi after the Jordanian militant was killed in a U.S. airstrike in June 2006.

Iraqi forces announced last May that al-Masri had been killed in fighting north of Baghdad. But al-Qaida in Iraq contradicted that report by releasing an audio recording from the Egyptian-born militant.

Last month, a message said to be from al-Masri threatened a fresh campaign of attacks against U.S. troops and vowed to behead a U.S. soldier.

In other news Thursday from Iraq, a car bomb exploded in the Mansur district of Baghdad, killing seven people and wounding at least 19 others. Officials say three policemen were among those killed.

Also in the capital, at least one rocket landed in the center of the city, killing at least two people and wounding four others.

In the southern port city of Basra, the U.S. military says several rockets hit a coalition military base Thursday, killing two civilian contractors and wounding eight people. The military says six militants were killed in a counter attack.

Earlier, medical officials said seven people were killed in fresh clashes between Shi'ite fighters and U.S. forces in Baghdad's Shi'ite stronghold, Sadr City.

U.S. and Iraqi forces have fought fierce battles in Sadr City against Shi'ite militiamen loyal to radical cleric Moqtada al-Sadr for the past month.

Some information for this report provided by AP and Reuters.