A US Marine helicopter transporting troops crashed in Iraq’s the desert of western Iraq, killing 31 people, American military officials said.

Insurgents staged attacks against US forces, schools to be used as polling stations and political party offices today, as they pressed a bloody campaign to undermine Iraq’s weekend elections.

Iraqi commanders are pulling troops out of the north of the country to back up Republican Guard units crippled by days of US attacks in the south, US defence officials said today.