The protesters, supporters of rebel Shiite cleric Moqtada Sadr, hanged an effigy of President George Bush from the pedestal that once supported the statue of Saddam Hussein toppled when U.S. troops took over Baghdad in 2003, The New York Times reported.

Demonstrators chanted "Allahu akbar" -- "God is great" -- and "No, no to America; No, no to Israel" during the rally staged as the Iraqi Parliament broke from discussing the status of forces agreement that Prime Minister Nouri al-Maliki negotiated with the United States and which must be approved by the Iraqi Parliament.

Under the status of forces agreement, U.S. troops will withdraw from Iraqi towns and cities in 2009 and pull out completely from Iraq by the end of 2011. It would be effective after the U.N. mandate authorizing foreign troop presence in Iraq expires Dec. 31.

An aide to Sadr said the cleric's supporters, estimated to be at least 10,000, were "coming out to prove the security pact is worthless," the BBC reported.

"Today is the day of Iraqi unity among Arabs, Kurds, all communities of Iraq, to reject the security pact," Hazim al-Araji said.