The UN’s envoy warned Baghdad on Saturday that Iraqi politicians must move forward on forming a government or risk the country descending into "chaos".

The UN's envoy warned Baghdad on Saturday that Iraqi politicians must move forward on forming a government or risk the country descending into "chaos".

Nickolay Mladenov said Iraq's bickering MPs would have only themselves to blame if they failed to make progress, a day before lawmakers were scheduled to meet.

"Failing to move forward on electing a new speaker, a new president and a new government risks plunging the country into chaos," he said in a statement.

"It will only serve the interests of those who seek to divide the people of Iraq and destroy their chances for peace and prosperity."

World powers and Iraq's top religious reference Ayatollah Sayyed Ali al-Sistani have appealed for lawmakers to put aside their seemingly intractable differences and form a united front against a Takfiri-led onslaught that has overrun swathes of the country.

But on July 1 the first parliamentary meeting since April elections ended in acrimony after Kurdish and Sunni Arab lawmakers walked out amid heckling and threats.

Another session was scheduled for the following week, but was postponed for more than a month until after the end of the Muslim fasting month of Ramadan.

"If serious solutions to the current problems are not found, then all political leaders will have to share their responsibility for failing to act with the necessary sense of duty at a time of crisis," Mladenov said.