At least 18 people have been killed and another 80 injured after a car bomb exploded in central Baghdad.

Police sources told Al Jazeera that the blast, in the Karrada neighbourhood of the Iraqi capital on Tuesday, caused the collapse of a building that belonged to the criminal investigation department of the interior ministry.

Hospital and police officials said the bomber tried to drive through a police checkpoint and the blast walls protecting the offices, which are in Tahariyat Square.

An interior ministry official said five policemen and 13 civilians were killed, adding that all had died in the blast while most of the wounded were pulled from underneath the rubble of the building.

Forensics lab hit

The attacker managed to evade tight security in the central neighbourhood of Karrada, where checkpoints are located at all the entrances and police conduct regular security searches.

Major General Qassim Atta, an Iraqi military spokesman in Baghdad, said the attack targeted the forensics institute, which has been bombed twice before.

"At 10.45am (0745 GMT) a suicide bomber raced his vehicle towards the institute", Atta said.

"The building collapsed soon after the explosion. Dozens of people usually work in the institute," he said.

The interior ministry official said the blast wrecked the laboratory.

Hotels targeted

The blast comes a day after three huge minibus bombs exploded across the capital killing dozens of people.

Those blasts targeted well-known hotels and came on the same day that the government announced the execution of "Chemical" Ali Hassan al-Majid, a cousin of Saddam Hussein, the ousted former president.

Iraqi politicians and US forces have warned of rising violence ahead of the March 7 elections, the second parliamentary ballot since the 2003 US-led invasion that ousted Saddam.