UDATED: Number of victims
At least 132 people have been killed and 520 injured in two car bomb attacks in Baghdad, Iraqi officials say, according to BBC.
The blasts hit the ministry of justice and a provincial government office near the heavily fortified Green Zone.
They came in quick succession at 1030 (0730 GMT) as people headed to work during the morning rush hour.
This is the deadliest attack in Iraq since August 2007 and comes three months after the US handed security control of cities to local forces.
The Iraqi authorities say that they believe these two attacks today and those of the 19th of August are linked.
Damascus [accused by Iraq over 19 August attacks] has strenuously denied any involvement.
But there have been warnings that as Iraq approaches parliamentary elections, which are due in the middle of next January, that insurgents and other fighters will try to cause more attacks to try to destabilise the situation here in Iraq.
The attacks have drawn comparison with those of 19 August, when truck bombs hit two ministry buildings and killed at least 100 people.
Iraq then blamed foreign fighters and accused Syria of involvement, demanding a UN investigation.
Prime Minister Nouri Maliki visited the site of Sunday's provincial government office attack on Haifa Street and later issued a statement blaming al-Qaeda and supporters of former president Saddam Hussein.
"These cowardly terrorist attacks must not affect the determination of the Iraqi people to continue their struggle against the remnants of the dismantled regime and al-Qaeda terrorists, who committed a brutal crime against civilians," he said.
"They want to cause chaos in the nation, hinder the political process and prevent the parliamentary election."
Plumes of smoke were seen rising in Baghdad on Sunday morning after two vehicles packed with explosives blew up just outside the International Zone, or Green Zone, the administrative heart of the capital.
There were conflicting reports from Iraqi police and other security officials about whether suicide bombers were involved.
Iraqi officials say the number of dead and wounded is likely to rise, as rescue workers dig through the rubble to search for survivors.
A number of workers for Baghdad's provincial council, which runs the city, were thought to be among the dead.
"I don't know how I'm still alive," local shop owner, Hamid Saadi, told Reuters by telephone from near the justice ministry.
"The explosion destroyed everything... it's like it was an earthquake, nothing is still in its place."
A number of bystanders blamed the security forces and politicians for failing to keep order.
Ambulance driver Adil Sami told Agence France-Presse: "We don't want the parliament any more - let them leave us alone, we can live in peace and solve problems ourselves."
Baghdad provincial council member Mohammed al-Rubaiey said: "This is a political struggle... Every politician is responsible and the government is responsible, as well as security leaders."
The BBC's Gabriel Gatehouse in Baghdad said he felt the force of the explosions, even though he was several miles away.
He says the finger of blame is likely to point to insurgents or foreign fighters trying to destabilise the security situation ahead of Iraqi elections in mid-January.
Overall, violence has dropped dramatically in Iraq compared to a year ago, but sporadic attacks still continue in several parts of the country.