Prime minister-designate Mohammed Shia al-Sudani was tapped to form a new government on October 13, raising hopes of an end to a year of deadlock since Iraq's last election, but the Shiite nominee has been locked in talks with potential partners over who gets which ministry.

"The session has been postponed," said Kurdistan Democratic Party lawmaker Sherwan Dubardany.

"Mr Sudani has not managed to reach agreement with the political blocs on cabinet appointments. We hope that in the coming days the blocs will come to understandings that allow a new date to be set."

The Coalition for the Administration of the State had said just Tuesday that they intended to hold the confidence vote this week.

The coalition includes the Coordination Framework, an alliance of powerful pro-Iran Shiite factions that holds 138 out of 329 seats in parliament.

Other members include a Sunni grouping led by parliament speaker Mohamed al-Halbussi, and two key Kurdish parties.

Under a power-sharing system adopted in Iraq in the aftermath of the US-led invasion of 2003, cabinet posts are shared between Iraq's ethnic and confessional communities.

"There will be no session on Saturday," said Thabet al-Abbasi, a lawmaker from Sunni Arab bloc Al-Siyada, adding that he hoped a new cabinet line-up would be thrashed out soon.

Under the constitution, Sudani has 30 days from his nomination to win a confidence vote in parliament.

The Coordination Framework's main rivals from Iraq's Shiite majority community, the movement of populist cleric Moqtada Sadr, has already said it will not join Sudani's government.