The shooting of Governor Ali al-Haidri in a roadside ambush showed insurgents' power to strike at the heart of the governing class, raising fresh doubts as to whether security forces can protect politicians and voters as the ballot draws near.

The assassination took place hours after a bomber rammed a fuel truck into a checkpoint near Baghdad's Green Zone, a sprawling compound housing the Iraqi government and the US and British embassies. The vehicle went up in a giant fireball that rocked the capital.

The blast killed eight police commandos and three civilians and wounded 60 people, bringing fresh scenes of bloodshed to Baghdad's streets a day after 17 security men died in a string of ambushes and explosions across the country.

The attacks were the latest in a drive by Sunni insurgents trying to force out US-led forces, cripple the American-backed interim government and scare voters away from the polls. Iraqi leaders say guerrillas also want to provoke sectarian civil war.

Voicing sadness at Haidri's assassination, Secretary of State Colin Powell said: "It once again shows that there are murderers and terrorists and former regime elements in Iraq that don't want to see an election.

"They want to go back to the tyranny of the Saddam Hussein regime and that is not going to happen," he told a news conference in the southern Thai resort island of Phuket as he began a visit to tsunami-hit countries in Asia.

Haidri and one of his bodyguards were killed when gunmen opened fire on his car in western Baghdad, police sources said. He was the most senior official assassinated in the city since the head of the Governing Council was killed last May.

Haidri, the head of Baghdad province, had survived a previous assassination attempt in September.

Insurgents have repeatedly attacked Iraqi officials as well as members of he country's fledgling security forces, accusing them of collaborating with foreign occupiers.

VULNERABLE SECURITY FORCES
Yesterday's powerful explosion hit a roadblock near the police commando headquarters on the outskirts of the Green Zone.

The choice of targets again showed the vulnerability of Iraq's new security branches, which have gained a reputation for ineffectiveness even as they undergo crash training to take over eventually from American-led forces.

The latest attacks have been concentrated in Baghdad and the restive Sunni heartland of northern Iraq.

There was also a fresh strike against foreigners. Four security contractors, three Britons and an American, were killed Monday in a bombing in Baghdad, a diplomat said.

Insurgents blew up a Turkish fuel tanker in the northern city of Mosul yesterday, killing the driver, witnesses said.

The Iraqi militant group Army of Ansar al-Sunna, which last week mounted the deadliest suicide attack on Americans since the start of the war with an attack on a US base in Mosul, claimed responsibility for a separate bombing in west Baghdad Monday.

An explosives-laden car trying to ram through a checkpoint near interim Prime Minister Iyad Allawi's party offices exploded, killing two police officers and a civilian.

Osama bin Laden and Islamist groups have pledged to wreck the elections as part of a holy war.

US and Iraqi officials ushered in the New Year by warning they expected a spike in pre-election attacks, but pledging to do everything possible to safeguard what they say will be the country's first free elections since the 1950s.

Outside Baghdad, bloodshed has been heaviest in areas dominated by Saddam's once-privileged Sunni minority, which now faces the prospect of elections cementing the newfound political power of the long-oppressed Shia majority.

Two shells landed in the grounds of a Baghdad mosque where Sunni Muslim clerics and politicians were meeting to discuss the coming election, but no one was hurt, witnesses said.