Two suicide bombers killed 45 people and wounded 150 when they blew themselves up at a crowded market in the Iraqi town of Hilla today.
At least 56 people were killed in Iraq as bomb and mortar attacks in Baghdad killed 11 people.
The new violence occurred as new figures showed civilian deaths rose to a record level in January.
The data from an Interior Ministry official, widely viewed as an indicative but only partial record of violent deaths, showed 1,971 people died from attacks in Iraq in January, slightly up from the previous high of 1,930 deaths in December.
The first suicide bomber in Hilla, a Shi'ite Muslim town 60 miles south of Baghdad, blew himself up when police tried to frisk him outside the central market.
A second suicide bomber struck soon afterwards, police said.
A man strapped with explosives also blew himself up in a minibus in the religiously mixed Baghdad district of Karrada, killing six people and wounding 12.
Elsewhere in the capital, a car bomb in the busy shopping district of Rusafi, killed three people and wounded seven and 10 mortar bombs hit Adhamiya, a mainly Sunni Arab area in northwest of the capital, killing two and wounding nine.
Thousands of US troops are being sent to Baghdad to help Iraqi security forces in what is being widely seen as a final attempt to avert all-out sectarian civil war between Iraq's Shi'ite majority and Sunnis once dominant under Saddam Hussein.