Meanwhile, four US servicemen were killed as the Pentagon announced that US forces in Iraq have swelled to 161,000, their highest level since the March 2003 invasion.
Shortly after registration had closed for the December 15 election, a senior member of the electoral commission, Farid Ayyar, announced that "400 lists have been put forward".
The dominant Shiite "United Iraqi Alliance", set up by half a dozen factions to compete in January's general election - the first since the 2003 US-led invasion - remains in place.
But the Alliance, dominated by the Supreme Council for the Islamic Revolution in Iraq and the Dawa party, has lost one of its factions, led by deputy Prime Minister Ahmed Chalabi who is fielding his own separate list.
Another Shiite group, comprising supporters of firebrand cleric Moqtada Sadr, has joined the Alliance instead.
The Alliance won 140 of parliament's 275 seats in the January election.
Chalabi, a former Pentagon favourite, is heading a new National Congress for Iraq list.