Crisis talks between political leaders set for Friday, a day after Iraq's worst attacks in four months, were cancelled amid a worsening row that has seen its premier threaten to dissolve power-sharing.
Sunni Vice President Tareq al-Hashemi, who is wanted on charges of running a death squad, blamed the crisis on Shiite Prime Minister Nuri al-Maliki, and accused the Iraqi leader of behaving like now-executed dictator Saddam Hussein.
Maliki, meanwhile, has called for his Sunni deputy Saleh al-Mutlak to be sacked, and the Sunni-backed Iraqiya bloc, to which both Hashemi and Mutlak belong, has boycotted both parliament and the cabinet.
Tensions were further heightened on Thursday, when insurgents carried out coordinated attacks in Baghdad that killed 60 people and wounded nearly 200, while violence elsewhere in the country claimed another seven lives.
In an interview with the BBC's Arabic Service, Hashemi blamed Maliki for starting "a national crisis, and it's not easy to control."
"Iraqis have a right to be worried," he added.
Hashemi, who has denied the terror charges against him and is currently holed up in Iraq's autonomous Kurdish region, said Thursday's attacks occurred because the authorities were too busy chasing "patriotic politicians".
"What happened today shows the deficiency and it's a good evidence for the lack of control over administration of the security brief, because the security services are pointed in the wrong direction."
The vice president also told US magazine Foreign Policy that "many of Saddam's behaviours are now being exercised by Maliki unfortunately".
"The judicial system is really in his pocket," he added.
His remarks echo those of deputy premier Mutlak, who has likened the Shiite-led government to a "dictatorship", and said Maliki is "worse than Saddam Hussein".
It was those comments that prompted the prime minister to ask parliament to sack his deputy.
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Thursday's violence was the worst since August 15, when 74 people were killed in a series of attacks across 17 Iraqi cities.
The mayhem involved more than a dozen bombings across the capital which killed 60 people and wounded 183 others.
In the immediate aftermath of the attacks, parliament called for an urgent session of political leaders to be held on Friday, the Muslim day of prayer and rest, but the meeting was later cancelled with officials giving differing accounts of the reasons why.
Aidan Helmi, media adviser to parliament speaker Osama al-Nujaifi said the indefinite postponement was because MPs were unable to visit Baghdad due to Thursday's attacks. Helmi said it was unclear when the talks would be held "because there are many holidays coming up."
But a parliament official, speaking on condition of anonymity, told AFP the talks were cancelled because Maliki's National Alliance refused to attend if Iraqiya did not lift its boycott.
Meanwhile, US Vice President Joe Biden called Iraqi President Jalal Talabani, a Kurd, to discuss "all the difficult issues on the Iraqi political scene," Talabani's office said.
Biden supported efforts to bring Iraq's leaders together "to resolve problems through serious dialogue and in a peaceful way", the statement said.
In Baghdad, US army chief of staff General Ray Odierno, the former head of US forces in Iraq, met with Maliki and parliament speaker Osama al-Nujaifi, statements from their respective offices said.
The political dispute triggered demonstrations in the predominantly Sunni cities of Samarra and Ramadi, with hundreds of people calling for authorities to ensure Hashemi faced a fair trial.
The crisis comes just days after US troops completed their withdrawal, leaving behind what US President Barack Obama had described as a "sovereign, stable and self-reliant Iraq."
The White House insisted Iraq's security forces were capable in the face of Thursday's "heinous" attacks.
The US embassy said it was "especially important during this critical period that Iraq's political leaders work to resolve differences peacefully."
UN special envoy to Baghdad Martin Kobler slammed the "horrendous" attacks, and said Iraq's leaders must "act swiftly, responsibly and in unity."