A loud explosion rattled central Baghdad Saturday afternoon, shaking the windows in buildings, but there was no word on what caused the blast in the capital city, regularly convulsed by mortars, rockets and bombs.

In the waning moments of 2004, interim Prime Minister Iyad Allawi addressed Iraqis in a televised message, telling them the next year, with its January 30 national elections promised to be decisive for Iraq.

His vision and those of a collection of radical Islamist groups denouncing the polls highlighted the stark difference in the paths Iraq could venture down over the coming year.

In a somber beginning to the New Year, 15 ambulances, their sirens silent, one carrying a black banner, drove through western Baghdad, with the corpse of an ambulance driver struck down Friday when a random bullet whizzed into his vehicle.

Sabih Katta had been traveling central Baghdad's treacherous Haifa street to pick up injured Iraqis from a shoot-out when he, himself, was shot dead, his mourning colleagues told AFP Saturday.

He had already whisked away three injured children to Karkh hospital before returning to the deadly street, a haven of insurgents, one final time.

The middle-aged men carried Katta's plain wooden coffin to the cemetery, some of them crying and others shouting "God is Great" as they buried their fallen colleague.

Violence kept up its blistering pace in the Sunni Muslim heartland, north and west of Baghdad, the breeding ground of former regime loyalists, Islamists and criminals said to be driving the insurgency forward.

Two national guardsmen were killed and six wounded in a mortar strike at 6:00 am (0300 GMT) on their base in Isaki, 20 kilometrees south of Samarra, Captin Mohamed Qassem of the national guard told AFP.

Since Tuesday, Iraqi security forces were targeted in a series of brazen attacks that left more than 100 killed. Rebel attacks have claimed the lives of at least 1,000 police since the fall of Saddam's regime in April 2003.

Near the oil refinery town of Baiji, one Iraqi civilian was killed and four others wounded, including a woman and a child, when insurgents and national guardsmen traded fire pre-dawn Saturday in the town of al-Sainiya, police said.

Also Saturday morning, police recovered the corpses of two Iraqi truck drivers by the banks of the Tigris river in Balad. The pair worked for a trucking firm doing business with the US military, police said.

Near the northern oil centre of Kirkuk, gunmen killed a police lieutenant outside his house in Taza, police said.

A US marine was killed in action in Iraq's western province of al-Anbar, home to Fallujah, late Friday, the military said in a statement.

No further details were available from the military.

But the latest loss of life marked the end to the deadliest six month period for US troops in Iraq since they invaded the country, with a total of 504 soldiers killed, figures showed.

Allawi presented a stoic image to fellow Iraqis Friday night, fully aware of the importance of his words at the end of a tumultuous and violent year.

"The new year will be decisive in the history of our nation and its future," said the premier in the message aired on state-owned television Al-Iraqi.