|Hilla is a predominantly Shia city, located 100km south of Baghdad, Iraq's capital [Reuters]
At least 20 policemen have been killed in Iraq after a suicide bomber blew up a vehicle packed with explosives outside a police station in Hilla, a predominantly Shia city, 100km south of Baghdad, the capital.
Another 80 officers were wounded after the bomber rammed his car into the entrance of the police headquarters to unleash a powerful blast while policemen were changing work shifts on Thursday.
"More than 20 were killed, 80 wounded. Four are missing. All of them are from the police because the explosion happened at one of the main police headquarters," Sadeq al-Muhanna, Babil province deputy
Muhanna said a police expert had determined that the plastic explosive C-4 was used in the attack.
A hospital source in Hilla said the blast killed 25 and wounded 83.
Among those killed in the blast, which occurred at 0700 local time, were a police captain and a first lieutenant.
A police official said the explosion badly damaged several sections of the police station and knocked over some of the concrete barriers that surround the building.
Several nearby houses and shops were also seriously damaged.
Security forces cordoned off the blast site, prohibiting journalists from entering the area.
Iraq's army and police have been on high alert since US commandos killed Osama bin Laden, the al-Qaeda leader, on Sunday.
Al-Qaeda operatives have vowed revenge for the death on Sunday. Nobody has so far claimed responsibility for Thursday's attack.
"Although it is too early to pin the responsibility on one party, suicide explosions are mostly done by al-Qaeda and we expect [al-Qaeda] is behind this explosion," Muhanna said.
"We said before and we say it again, al-Qaeda will not be finished by the killing of its leader."
On Monday, four people were wounded after a bomb attached to a car exploded in a parking lot in Hilla.
Hilla, a predominantly Shia area, lies just beyond the edge of a religiously mixed area south of Baghdad that was dubbed the "triangle of death" during the sectarian bloodshed that peaked in Iraq in 2006 and 2007.
Violence is down in Iraq from its peak, but attacks remain common. A total of 211 Iraqis were killed in violence in April, according to official figures.