Iraq's largest Sunni Arab political bloc has announced its withdrawal from Prime Minister Nouri al-Maliki's coalition government, in a blow to efforts towards national reconciliation.

A spokesman for the Iraqi Accordance Front, Rafaa al-Issawi, said the bloc's six Cabinet ministers are submitting their resignations Wednesday. The spokesman said the Shi'ite led government has failed to meet the bloc's demands.

Last week, the bloc gave the prime minister a list of demands, including dealing with Shi'ite militias and reforming the conduct of raids and arrests.

In Washington, the White House downplayed the significance of the Sunni bloc's withdrawal. A spokesman said the bloc is not withdrawing completely from the political process, and that some Sunni Arabs remain in top positions.

The Accordance Front has been boycotting Cabinet meetings since June to protest legal proceedings against Culture Minister Asad al-Hashimi, who is accused of arranging to have another politician killed.

Some information for this report was provided by AP and Reuters.