The latest boycott -- by four ministers from a non-sectarian party -- brought to 17 the number of members of the Shia-led coalition to have walked out, tendered their resignations or withdrawn from cabinet meetings.

Hopes that the so-called national unity coalition can be saved now depend on the senior leadership of the rival parties cutting a new power-sharing deal that can convince the bitter Sunni minority to return to the fold.

"The government cannot survive all these defections," said Joost Hiltermann, the chief Iraq expert at the International Crisis Group think tank, after the secular Iraqi National List said its four ministers are boycotting cabinet.

"The Shias and the Kurds don't want to cede power to people they don't trust. But if they don't, there won't be reconciliation. Then all we can look forward to is civil war," he told AFP by telephone from Amman.

"Frankly, even with everyone in, there was total paralysis of government. Everyone is waiting for the top leadership to meet and cut a different kind of deal," he noted, with pessimism.

Since the US-led invasion of March 2003, Iraq has plunged into an abyss of overlapping civil conflicts that have divided its rival religious and ethnic communities, and left tens of thousands of civilians dead.

Last year's formation of an elected government of national unity held out the promise of reconciliation, but Maliki's rule has been undermined by bitter sectarian rivalries both within and outside his fragile coalition.

Sheikh Khalaf al-Ilayan, a senior lawmaker in the National Concord Front that resigned on August 1, said the government has failed on every level.

"The government has failed because it has failed to stick to its political obligations to its members. As so many have withdrawn, the government has no right to make decisions now," he said.

"If I were prime minister I would have resigned. But America thinks otherwise. This is against everything that is right," he said.