Mobile footage captures blast in the Iraqi capital
At least 132 people have been killed and 520 injured in two car bomb attacks in Baghdad, Iraqi officials say.
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.
Gabriel Gatehouse, BBC News, Baghdad
The Iraqi authorities say that they believe these two attacks today and those of the 19 August are linked. Damascus [accused by Iraq over the 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 cause more attacks to try to destabilise the situation here.
The Americans officially pulled back from urban areas at the end of June. The Iraqi security forces are now in charge. They have been trumpeting their success here. But these massive explosions and the ones on 19 August will raise serious questions about how capable they are of maintaining security.
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.
The US condemned the latest attacks as "hateful".
Prime Minister Nouri Maliki visited the site of Sunday's provincial government office attack near 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."
President Jalal Talabani said: "The perpetrators of these treacherous and despicable acts are no longer hiding their objective... they publicly declare that they are targeting the state."
The White House said President Barack Obama had spoken to Mr Maliki and Mr Talabani to pledge his support.
Mr Obama said the attacks were an attempt to derail the peace process.
"These bombings serve no purpose other than the murder of innocent men, women and children, and they only reveal the hateful and destructive agenda of those who would deny the Iraqi people the future that they deserve," Mr Obama said in a statement.
The UK's Foreign Secretary David Miliband said "such acts of terrorism can have no justification, and must be condemned without reservation".
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.
The Iraqi authorities said the attackers were suicide bombers.
Their vehicles were driven into parking bays and detonated, officials said.
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.
DEADLIEST ATTACKS SINCE 2003
Aug 2007: More than 500 killed in attacks on villages near Sinjar
Jul 2007: 150 killed in truck bombing in Tuz Khurmato
Apr 2007: 191 killed in car bombings in Baghdad
Mar 2007: 152 killed in truck bombing in Tal Afar
Feb 2007: 135 killed in truck bombing in Baghdad
Nov 2006: 202 killed in multiple blasts in Baghdad
Mar 2004: 171 killed in bombings in Baghdad and Karbala
Source: News agencies, BBC
"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.
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