At least 18 people were killed and some 80 others injured when a suicide minibus bomber struck the government forensics building in central Baghdad on Tuesday, an Interior Ministry source said.

"Our reports said that the toll rose to 18 killed, including five policemen, and some 80 others wounded by the suicide bombing carried out by a KIA minibus," the source told Xinhua on condition of anonymity.

Earlier, the source put the toll at five killed and 20 injured.

The attack took place at about 10:45 a.m. (0745 GMT) when a suicide bomber drove an explosive-laden minibus into the building of the Interior Ministry's forensic department close to the Taharriyat Square in Karrada district, the source said.

The department's building collapsed soon after the powerful blast as dozens of the department's workers were inside, he said.

The blast also destroyed several nearby buildings and shops, along with many civilian cars.

Iraqi security forces cordoned off the scene and blocked several main streets leading to the site, while ambulances and civilian cars were transporting dozens of victims to Baghdad hospitals.

The blast came a day after the three suicide car bombings targeted major Baghdad hotels that killed at least 36 people and wounded some 70 others.

Sporadic attacks continue in Baghdad as part of recent security deterioration which shaped a setback to the efforts of the Iraqi government to restore normalcy in the country ahead of the country 's national polls slated on March 7.