The developments highlighted bickering among political leaders despite calls for unity to see off foreign backed offensive that has overrun swathes of territory and which the security forces have struggled to repel.

The swift advance has displaced hundreds of thousands, alarmed the international community and heaped pressure on incumbent Prime Minister Nuri al-Maliki as he bids for a third term in office.

But the government formation process, which international leaders and top clerics have urged be expedited, was dealt a blow when a parliament session scheduled for Tuesday was postponed due to persistent disunity.

Multiple officials and a lawmaker, all speaking on condition of anonymity, said the meeting had rescheduled for August 12 because MPs could not agree on a new speaker.

More than two months after elections in which Maliki's camp won the most seats, though not a majority, parliament has yet to begin the process of choosing the country's top three positions, which according to an unofficial deal are split between the Shiite Arab, Sunni Arab and Kurdish communities.

A session last week ended in chaos, with MPs trading heckles and threats before some of them eventually walked out, forcing an adjournment, with the UN's special envoy warning that further delays risked plunging the country into "Syria-like chaos".

NJF/NJF