Baghdad: An onslaught on a convoy transferring inmates north of Baghdad left at least 60 dead on Thursday, even as politicians and diplomats stepped up efforts to end Iraq`s worst crisis in years.
Most of those killed in Taji, 25 kilometres (15 miles) north of Baghdad, were prisoners whose escort was attacked and were described by police as being mostly Sunni militants charged with terrorism.
Explosions from the attack were heard in some neighbourhoods of the capital, where UN chief Ban Ki-moon landed today on an unscheduled stop in his Middle East tour.
"At least 60 people, prisoners and policemen, were killed in a suicide attack followed by several IEDs (improvised explosive devices) and shooting," an interior ministry official told.
One security source said the inmates were being transferred as a precautionary measure after Taji prison was hit by mortar fire yesterday.
However the exact circumstances of the attack were not immediately clear, nor how many attackers were dead and how the prisoners they were apparently trying to free were killed.
The bus was believed to be transporting around 60 prisoners and medics said that some 50 of those killed in the pre-dawn attack were inmates.
Most of them were burnt beyond recognition, the medics said.
Government forces were recently accused by rights watchdogs of having executed more than 250 prisoners since June 9.
Among the allegations are that members of the Iraqi security forces shot prisoners, on the grounds they were sympathetic to advancing forces from the Islamic State (IS) jihadist group, that jails were set on fire and that grenades were tossed into cells.
Since it launched a sweeping offensive on June 9, IS and allied Sunni groups have conquered the country`s second city of Mosul, overrun large swathes of five provinces and declared a "caliphate" straddling Iraq and Syria.
The onslaught has fanned the flames of sectarian tension between Iraq`s Shiite majority and sunni minority that had already claimed thousands of lives this year alone.
Prime Minister Nuri al-Maliki`s alliance comfortably won elections in April but he has faced mounting domestic and foreign pressure to step aside since the flare-up.
The Shiite premier has accused the Sunni mainstream of condoning the Islamic State`s offensive and "dancing in the blood" of the jihadist onslaught`s victims.
But many retort it was Maliki`s own brand of sectarian politics that brought the country to the brink of collapse.
In his talks with Maliki, Ban Ki-moon was expected to highlight the plight of the 600,000 Iraqis displaced over the past few weeks and encourage the country`s fractious politicians to speed up the government formation process.