At least 66 people, most of them civilians, were killed in violence in Iraq on Sunday.
As night fell, three car bombs exploded in the Shia district of Sadr City in Baghdad, killing at least 46 people and injuring more than 90.
The first two blasts occurred at the Ula market, followed by a third in the Kayara market. A fourth was defused.
Sadr City, a stronghold of radical cleric Moqtada Sadr, has been relatively free from violence recently.
Earlier, about 20 people had been killed in a series of shootings, mortar attacks and roadside bombs.
But Sunni-backed insurgents have been seeking to spark sectarian violence in Iraq by repeatedly targeting the country's majority Shia population.
The force of the large explosions totally destroyed some shops, burned out cars and sent plumes of smoke billowing into the air.
"People were torn to pieces," a witness at the scene of one of the blasts told Reuters. "Nobody knows the number of casualties. It's a lot, it's a lot," he added.
A Reuters reporter said there was chaos at a hospital in Sadr City where casualties were taken, with wounded lying on the floor as well as stretchers, while distraught relatives wept nearby.
In other violence elsewhere in Baghdad, at least two people were killed when a shell fell on their house during a series of mortar attacks.
Three people were found shot dead in their car in southern Baghdad and the bodies of eight others, hands bound, blindfolded and showing signs of torture, were found in a south-eastern suburb.
At least six civilians also died when a car bomb exploded near a US military patrol.
Parliamentary sitting changed
The violence occurred as the trial of former President Saddam Hussein and seven co-accused on charges of mass murder resumed after a 10-day break.
For the first time three of Saddam Hussein's co-defendants gave their side of events surrounding a 1982 massacre in Dujail in which 148 Iraqi Shias were killed.
The BBC's Jim Muir in Baghdad says that many now see the only hope of curbing the unrest as being the rapid formation of a national unity government.
Nearly three months after the elections that is still not an immediate prospect, but under prodding from the US ambassador in Iraq, the first session of the new parliament has at least been brought forward by three days, our correspondent says.
Iraqi President Jalal Talabani announced that the country's new parliament will now meet on Thursday.