At least six police officers and 30 prisoners were killed in a riot at a jail in north-eastern Iraq, during which another 40 inmates escaped, authorities said today.

There were conflicting reports over casualties in the incident at the Khalis prison in Diyala province. Two provincial police officials and a medical official put the toll much higher, saying 51 inmates and 12 policemen were killed, while more than 200 inmates escaped.

Interior Ministry spokesman Brigadier General Saad Maan put the death toll at 36, including six police officers and 30 prisoners, and said 40 inmates escaped.

He told the Associated Press that a fight broke out among the inmates of the prison and when guards went to investigate, they were overpowered and had their weapons taken. Some of those who escaped were wanted on terrorism charges, he added. He said security forces had cordoned off the area and were hunting for the escaped inmates.

The town of Khalis is about 80 kilometres north of Baghdad.

In a statement carried on militant websites, the local chapter of the Islamic State group gave a completely different account of the incident, describing it as a co-ordinated operation involving the use of multiple explosives outside the prison. The statement claimed that 30 Islamic State members were among those who escaped.

Brig Gen Ibrahim had originally denied there was any external force involved and he did not immediately respond to requests for comment on the militants' version of events.

Jailbreaks are common in Iraq and usually a result of assaults from militants seeking to free their comrades in prison. The most spectacular one was in mid-2013, when militants carried out a carefully orchestrated attack with mortar shells and suicide bombers on Iraq's infamous Abu Ghraib prison, freeing more than 500 inmates.

Meanwhile, a car bomb exploded in Baghdad's central Karrada area today, killing at least eight civilians and wounding 28, a police officer said.

Among the dead were Shiite pilgrims preparing for next week's major event commemorating the anniversary of the 8th century death of a revered religious figure, Imam Mousa al-Kazim. Thousands of pilgrims typically march to his shrine in northern Baghdad to commemorate his death.

No group immediately claimed responsibility for the bombing, but it bore the hallmarks of the Islamic State extremist group, which has carried near-daily attacks - along with other Sunni militant groups - against the Iraq's Shiite majority, government officials and security forces.

The Islamic State group considers Shiites heretics. It captured large chunks of territory in western and northern Iraq last year, plunging the country into its worst crisis since US troops left at the end of 2011.

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