A police officer inspects burnt vehicles at the site of a car bomb attack in Baghdad February 25, 2007. [Photo: Reuters]

The death toll rose to 40 people killed and up to 35 wounded when a suicide bomber blew himself up outside a collage campus in eastern Baghdad on Sunday, an Interior Ministry source told Xinhua.

"The death toll climbed to 40 people killed and 35 others wounded, most of them were students," the source told Xinhua on condition of anonymity.

Earlier, the source put the death toll at 20 killed and 30 wounded.

"A suicide bomber wearing an explosive-packed vest tried to enter the college's campus in the Talbiyah neighborhood, but the guards stopped him and he detonated his explosives," the source said.

Meanwhile, a series of car bombs and mortar attacks rocked Baghdad on Sunday despite the major offensive launched by the U.S.and Iraqi forces in Baghdad which aimed at curbing violence.

On Sunday morning, a car bomb parking some 100 meters away from the Iranian embassy near the Green Zone in central Baghdad, detonated and killed two civilians and wounded four others, the police said.

Another car bomb went off near the Jabbar Abu al-Sharbat soft drink store in the Karradah neighborhood in central Baghdad, wounding four people, the police said.

The explosion sent a plume of black smoke into the air.

Meanwhile, central Baghdad also witnessed mortar rounds attack, which wounded three people in the Elwiyah neighborhood, according to the source.

Earlier, rockets also hit the Abu Dshier neighborhood in southern Baghdad, wounding two people, he added.

Violence persisted in Baghdad despite the presence of some 85,000 U.S. and Iraqi security forces across the capital in a major offensive aimed at curbing insurgency and sectarian violence in the war-torn country.