Iraq's new Parliament deadlocked less than two hours into its first session on Tuesday when minority Sunnis and Kurds walked out, dashing hopes for the quick formation of a new government that could hold the country together in the face of a Sunni Islamist insurgency.

Acting speaker Mahdi al-Hafidh ended the proceedings on Tuesday after most of the 328-member legislature's Sunni and Kurdish lawmakers did not return following a short break, depriving Parliament of a quorum. The entire session, from the opening national anthem to al-Hafidh's final words, lasted less than two hours.

Shiite Prime Minister Nouri al-Maliki has made the formation of a new government a pressing concern as he seeks to rally the country to fight off jihadi fighters led by the Islamist State militant group - until recently known as the Islamist State of Iraq and the Levant.

Having taken huge swaths of land in Syria and more recently Iraq, the group made statements announcing its own "caliphate" ruled by Islamic law, calling on Sunni Muslims to join their ranks.

The militant onslaught has tapped into deep-seated grievances among the country's Sunni minority and stoked fears of more widespread fighting between Shiites, Sunnis and ethnic Kurds across Iraq. The formation of a unity government bringing together all the major groups is seen by many as a necessary step to defeating the insurgency.

The impasse, which was largely expected despite intense political pressure to make a quick deal, prolongs what has already been days of intense jockeying as political blocs try to decide on a new prime minister, president and speaker of parliament. The country's top Shiite cleric, Grand Ayatollah Ali al-Sistani, urged lawmakers last week to agree on the three posts before Tuesday's meeting in hopes of averting months of wrangling that could further destabilize the country.

The main sticking point is the job of prime minister, which holds the main levers of power. Under an informal system that took hold after the 2003 US-led invasion, Iraq's prime minister is chosen from the Shiite community, the president from the Kurdish minority and the speaker of parliament from the Sunni community.

Maliki, who has held the post since 2006, is being pressed to step aside as his failure to promote reconciliation has been blamed for stoking the insurgency. Sunnis and Kurds, both of whom accuse al-Maliki of breaking promises and attempting to monopolize power, demand that he be replaced.

But al-Maliki has shown no willingness publicly to bow out. His bloc won the most votes in April elections, which traditionally would give him first crack at forming a new government. The current crisis in Iraq, however, has altered political calculations, and many of al-Maliki's former allies, and even key patron Iran, have begun exploring alternatives to replace him.