"I have ... submitted the resignation of the government, and I have declared that I will not be a candidate to head the [next] government," a statement from his office quoted him as saying.

Hariri, who has been prime minister for much of the past 12 years, had first announced he planned to resign at the beginning of last month amid a political crisis over Syria's influence in the country's affairs.

He submitted his resignation to President Emile Lahud, his main political rival who is favoured by Lebanon's political masters in Damascus.

A cabinet dissolution had been expected as a formality before Lahud begins his next presidential term in late November.

However, Hariri had been expected to be reappointed after he ultimately sided with Lahud on amending Lebanon's constitution to extend the president's term - a Syrian-backed move that drew international condemnation.

Hariri's decision could be political posturing to secure a stronger mandate from parliament that, should he ultimately accept the job, would better position him in his long-standing power struggle with Lahud.

Syrian role

The move comes amid a deadlock between Syrian President Bashar al-Asad's government and the United Nations, which on Tuesday repeated a call for Syria to pull its troops out of Lebanon - a demand that Damascus swiftly rejected.

The Lebanese parliament's extension of pro-Syrian Lahoud's term was a direct challenge to the UN Security Council, which also demands Syria withdraw its remaining 14,000 troops from Lebanon.

Hariri's fate had been uncertain for weeks, with no clear indication if he would resign but form a new government, or leave office altogether.