BAGHDAD (Reuters) - Iraq's Supreme Court rejected appeals lodged by Iran-backed Shi'ite factions against the results of a parliamentary election on Monday, the chief judge said, derailing their attempt to overturn the vote in which they performed poorly.

       The Iran-backed factions, including powerful armed groups, had alleged irregularities in the Oct. 10 vote. Judge Jassim Mohammed read out the ruling rejecting their appeal at the court headquarters in Baghdad.

       The biggest winner in the vote was the movement led by Shi'ite cleric Moqtada al-Sadr, an opponent of both Iranian and U.S. influence in Iraq, which won 73 seats, more than any other group in the fractious 329-seat house.

       Once the result is confirmed by the Supreme Court, negotiations are expected among Shi'ite, Sunni and Kurdish groups over the formation of a new government to replace the outgoing cabinet led by Prime Minister Mustafa al-Kadhimi.

       (Reporting by Ahmed Rasheed, Writing by Tom Perry; Editing by Andrew Cawthorne and Emelia Sithole-Matarise)