Baghdad, Iraq (CNN) -- The death toll from twin car bombings in Baghdad climbed to 160, with hundreds more wounded in the deadliest attack in the capital in more than two years, the Interior Ministry said Monday.
At least 540 people were wounded in Sunday's attacks.
One of the bombs exploded outside Baghdad's governorate building, the other outside the justice ministry. The bombs detonated in quick succession about 10:30 a.m., officials said.
Among the wounded were three American security contractors, the U.S. Embassy said, declining to provide further details. The area struck is close to the heavily guarded "green zone," which houses the embassy.
The blasts sparked questions about Iraq's security and national elections planned for January.
Iraqi Prime Minister Nuri al-Maliki, who visited the scene shortly after the explosions, said holding the elections as scheduled would send a strong message to the attackers.
"The cowardly attack ... should not affect the determination of the Iraqi people from continuing their battle against the deposed regime and the gangs of criminal Baath party, and the terrorist al Qaeda organization,'" al-Maliki said in a statement.
U.S. President Barack Obama called the attacks an attempt to derail progress in Iraq, and pledged to work closely with the country as it prepares for elections. Obama spoke with the prime minister and President Jalal Talabani to express his condolences and reiterate U.S. support.
In August, more than 100 people were killed in a series of bombings that led to tightened security in Baghdad. Blast walls were installed across the city and checkpoints added.
Two years earlier, three truck bombings had killed hundreds in Qahtaniya, in northern Iraq. Sunday's attacks were the deadliest on Iraqi civilians since the blasts in August 2007.