US President George W Bush told Iraqis to choose between "chaos and unity", but played down talk of civil war.
In the week since explosives demolished the Golden Mosque in Samarra, one of the holiest sites in Shi'ite Islam, sectarian violence has killed over 400 people, pitching Iraq toward a civil war that would inflame the Middle East and might thwart Mr Bush's hopes of withdrawing US troops.
In the latest violence, the mosque attack occurred in Baghdad’s north-eastern al-Hurriya neighbourhood and came just hours after three successive bombs went off in mixed Shiite-Sunni areas of the capital on Tuesday morning.
In one of Tuesday morning’s attacks, a suicide bomber wearing an explosives vest blew himself up next to a queue of people waiting to buy kerosene in Al-Amin, southeast Baghdad.
In the second of what appeared to be coordinated attacks, a car bomb exploded in the city's south-eastern district of Jadida, killing 24 people, an interior ministry official said.
Another six people were killed in a car bomb attack near a market in the central Karada district.
In other violence five bodyguards of Lieutenant General Daham Radi al-Assal, advisor to the Iraqi defence minister, were reported killed when a roadside bomb exploded near his convoy in eastern Baghdad and in the northern town of Mosul gunmen killed two policemen.
The latest bomb attacks hit Baghdad just one day after the authorities lifted a daytime curfew and a vehicle ban in the capital.
Unity urged
It was unclear whether the latest violence would strain efforts to lure Sunni parties back into talks on forming a new government after they left the negotiations last Thursday in anger over the attacks on their community.
Sunni participation in government is seen as crucial to ending the Sunni-dominated insurgency, which has plunged Iraq into chaos since US forces toppled Saddam's regime in 2003.
The main Sunni political bloc, the National Concord Front, has indicated it would return to talks on a new government only if Sunni religious sanctuaries seized by Shi’ite militias were returned to them.
Saddam's trial reopens
Meanwhile, that trial of former dictator Saddam Hussein and seven of his former cohorts is set to resume after it reopened on Tuesday.
The prosecution presented an execution order they claimed Saddam signed, showing that the former dictator had ordered the execution of 148 Shi’ites for a failed 1982 assassination attempt against him.
Neither Saddam or the other defendants questioned the validity of the documents.
Meanwhile, prosecutors also submitted a letter from Iraq's secret service, dated June 23, 1987, saying 46 of the victims had in fact died from torture rather than by hanging.