President Jalal Talabani, a Kurd, said the agreement might help to resolve the current political crisis in Iraq, adding that Sunnis are still welcome to join the new alliance. He said the agreement "was not struck in the interests of the signing parties, but in those of the Iraqi people and the government of national unity."
The announcement comes after days of political negotiations, which were boycotted by Sunni representatives.
The government of Prime Minister Nuri al-Maliki has been struggling to overcome the current crisis since the largest Sunni Muslim bloc, the Iraqi Accordance Front, and other ministers withdrew from the cabinet, leaving half the seats empty.
Al-Maliki this week called for a high-level summit of senior leaders from all the factions, but Sunni leaders have so far refused to participate.