The commander of U.S forces in Baghdad, Major General Joseph Fil, says violence in Baghdad has dropped significantly since the start of a security crackdown in Iraq in an effort to end sectarian violence.

But General Fil says the insurgents are closely watching the operation to determine what Iraqi and U.S. troops will do next.

Abu Ayyub al-Masri as shown from Iraqi government file tape in October

Earlier Friday, the U.S. military cast doubt on reports that al-Qaida in Iraq leader Abu Ayyub al-Masri was wounded in a clash with government troops.

Iraqi television, al-Iraqiya, had cited an Interior Ministry spokesman as saying al-Masri was wounded and his top aide was killed in a firefight with Iraqi police near the town of Balad, north of Baghdad.

The al-Qaida-affiliated militant group Islamic State of Iraq, in a posting on an Islamic militant Web site, denied that al-Masri was wounded.

Al-Masri, also known as Abu Hamza al-Muhajer, is an Egyptian who took over the leadership of al-Qaida in Iraq last year, after the group's top leader, Abu Musab al-Zarqawi, was killed.

In other news, Iraqi President Jalal Talabani said Iraq's biggest Shi'ite militia, the Mahdi Army, ordered some of its members to leave Iraq temporarily.

The Mahdi Army is loyal to radical Shi'ite cleric Moqtada al-Sadr, who Iraqi and U.S. officials say is already in Iran.

Some information for this report was provided by AFP and AP.