Coordinated blasts killed at least 25 people in the heart of Baghdad on Thursday near the heavily fortified Green Zone, where several Western embassies are located, police and medics said.
No one immediately claimed responsibility for the explosions, but Sunni Muslim insurgents have been redoubling their efforts to undermine Iraq's Shi'ite-led government and foment inter-communal conflict this year.
The brazen attacks in broad daylight will fan concerns about Iraq's fragile security, which has come under growing strain as the increasingly sectarian conflict in neighboring Syria threatens to upset its own Sunni-Shi'ite balance.
Police said two car bombs exploded in the Alawi district, one of them near the justice ministry building, before a suicide car bomber blew himself up near an interior ministry office.
A suicide bomber then walked into the Justice Ministry and militants attacked the building, clashing with Iraqi security forces, who eventually regained control.
"I went to the second floor to do something when I heard a big explosion, then a second one," said Ammar Ghanim, a policeman who was inside the ministry at the time of the attack.
"We heard shooting and a few minutes later three attackers wearing military uniform came up to the second floor and randomly started shooting," he said. "I got shot in the leg and I am very proud to have killed one of them (the attackers)."
Among the dead were at least 7 policemen and 15 civilians, police and medics said. Three militants were also killed. At least 50 people were wounded.
Iraq's power-sharing government has been all but paralyzed since US troops left more than a year ago and Prime Minister Nuri al-Maliki, a Shi'ite, is facing protests in the country's Sunni heartland, which shares a porous border with Syria.
Violence has intensified as Sunni opposition has swelled, and Iraq's al Qaeda affiliate has urged the protesters to take up arms against the government.
Security experts say al Qaeda-linked militants have been regrouping in the western province of Anbar and crossing into Syria to fight alongside mainly Sunni rebels against forces loyal to President Bashar al-Assad, an ally of Shi'ite Iran.