At least 12 people were killed and 29 others wounded on Monday when a bomb went off in a market northeast of Baghdad, a source from Diyala provincial police told Xinhua.

The blast occurred at about 5:00 p.m (1400 GMT) in a market in Khalis, 75km northeast of the capital, the source said, adding that a mortar round shelled the market minutes later.

Khalis is located in the volatile province of Diyala, which is believed to be a stronghold of Sunni militants.

Although the beleaguered Prime Minister Nuri al-Maliki announced his new Baghdad security plan earlier this month, vowing to crack down on all illegal armed groups "regardless of sect or politics", the violence continues to rage in the capital.

Earlier in the day, two car bomb blasts occurred in central Baghdad, killing some 75 people and wounding 160 others, an interior ministry source told Xinhua.

Last Tuesday, two car bombs and a suicide bomber killed 65 people and wounded 132 near a university in eastern Baghdad.

On Saturday, American forces also witnessed the bloodiest day in two years, with at least 24 servicemen being killed as U.S. military on Sunday sent about 3,200 new troops to Baghdad to support the upcoming security plan.

Editor: Yan