Meanwhile, Al-Qaeda and several other extremist groups have threatened to disrupt the Iraq polls and warned the people against taking part in the electoral process.

Thirty one US Marines were killed when a helicopter transporting them crashed in the desert of western Iraq.

Four other US Marines were killed in fighting in Anbar province and another in an attack on a US patrol near the northern town of Duluiyah yesterday, the deadliest day for the US forces in Iraq.

Besides, seven other people were killed in a car bomb attack on a police station in Kirkuk.

With only days before the election, guerrillas carried out a string of attacks targeting political groups and voting sites.

CHOPPER CRASH
US military transport helicopter crashed during sandstorms in Iraq's western desert yesterday, killing 31 people, all believed to be Marines, while insurgents killed five other American troops in the deadliest day for US forces since the Iraq war began, reports AP.

A Bush administration official said the cause of Wednesday's crash was not immediately known but that there was bad weather at the time. An Accuweather map of Iraq showed sandstorms in the western region of Iraq near the Jordanian border where the crash took place.

The CH-53 Sea Stallion was carrying personnel from the 1st Marine Division when it went down about 1:20am near the town of Rutbah, about 220 miles west of Baghdad, while conducting security operations, the military said in a statement.

It was also the deadliest day for US forces since the March 2003 invasion.

In Iraq's Anbar province, four US Marines were killed in fighting, the military said in a statement.

The statement gave no further details, but WABC reporter Jim Dolan, who was embedded with the troops who were attacked, said the deaths came when insurgents ambushed a Marine convoy leaving the town of Haditha, hitting a vehicle with a rocket-propelled grenade.

Also Wednesday, insurgents attacked a US Army patrol near the northern town of Duluiyah, killing one soldier and wounding two others, the US command said.

THREAT TO DISRUPT POLLS
The group of Al-Qaeda frontman Abu Musab al-Zarqawi, as well as several other extremist organisations, have vowed to disrupt the polls and warned the population against taking part in the electoral process.

Zarqawi, whose group claimed attacks on 12 polling stations Tuesday, has declared war on the elections.

"Trained snipers will be ready to kill the apostates who go to the electoral lairs," warned a statement signed by Zarqawi's organisation.

Voter turnout is expected to be extremely low in Sunni Muslim areas, due to the security threat and boycott calls by Sunni parties and clerics arguing that elections should not be held until all foreign troops leave Iraq.

But the incumbent prime minister, US-backed Iyad Allawi, signalled no interest in setting a timetable for a withdrawal of coalition troops.

"I will not set final dates because dates now would be both reckless and dangerous," Allawi told reporters on Tuesday.

CAR BOMB KILLS 7
Seven people were killed yesterday in a car bomb attack on a police station in Kirkuk, reports AFP.

Elsewhere, four American soldiers were wounded in a car bomb attack targeting a military convoy on the Baghdad airport road.

A string of other attacks rocked Iraq on Wednesday, including several against polling centres, as rebels stepped up their campaign of intimidation ahead of Sunday's polls, the first in the post-Saddam Hussein era.

Major General Turhan Yusef, police chief in the ethnically-divided northern city of Kirkuk, said three policemen, two soldiers and two civilians were killed in the blast.

Rebels pounded eight polling stations with rockets, mortar shells and bombs within a few hours in the same restive regions, Iraqi police and local officials said.

Three were hit in Baquba and two others outside the troubled town. A voting centre came under rocket fire in the town of Dhuluiyah, and another was hit by a bomb blast near Samarra.

A bomb also went off near a school in Baghdad that like many other schools is being turned into a polling station for the elections.