Insurgents shot dead five Iraqi policemen at a checkpoint and a car bomb killed four people in Baghdad yesterday, underscoring the dire security situation on the third day of violence since a new government was formed.

The shooting attack near a military college serving as a US military camp reinforced concerns that US-trained Iraqi forces still have a long way to go before they can take over security from American soldiers.

At least four civilians were killed and five wounded when a car bomb targeted a US military convoy near a technical college in the capital, police said. There was no word from the US military on whether any US troops were hurt.

In the three days since Iraq announced the formation of a government ? after three months of negotiations ? insurgents have carried out a furious sequence of bombings, including more than 15 car bomb blasts in Baghdad, killing dozens.

Iraqi officials say militants have capitalised on the months of political haggling over the government?s formation to step up their attacks in a campaign that has erased much of the optimism created by the Jan. 30 elections.

The political squabbling and renewed violence also appear to have fuelled sectarian tensions, with politicians struggling to balance the interests of Shi?ites and Kurds, who are the new powers, and the Sunnis who dominated Iraq under Saddam Hussein.

While most of the violence in the past three days has focused on the capital and nearby areas, there are still attacks in the country?s traditional hotspots. Guerrillas fired at least seven rockets into the city of Falluja on Saturday, killing three Iraqi civilians and wounding another, the US military said.

<B>Security crisis</B>

A US-led military offensive in November killed or captured hundreds of insurgents in Falluja, a former rebel stronghold, and destroyed the nerve centre of the guerrillas. Since then, militants appear to have taken their operations elsewhere.

They have stepped up activities in cities such as Mosul, where the US military said a bomb hidden in a shrine killed three Iraqi civilians on Saturday, and a suicide bomber attacked an American convoy, killing two Iraqis.

A US soldier was killed by small-arms fire on Saturday in the town of Khaldiya, about 130 km west of Baghdad, raising to at least 1,206 the number of American soldiers killed in action since the war that toppled Saddam started in 2003.

Iraqi politicians want to show their people that their own security forces can defeat Saddam loyalists and militant followers of al Qaeda?s leader in Iraq, Abu Musab al-Zarqawi, a Jordanian who is the most hunted man in Iraq, with a $25 million bounty on his head.

But America?s top general said this week insurgents were as strong as they were a year ago, mounting up to 60 attacks a day, despite the presence of about 140,000 US troops and more than that number employed in the Iraqi security forces.

Guerrillas seem to be implementing a ruthless new strategy of following up one suicide bombing with a second, aimed at police and security forces who rush to the scene.

In an audio tape put on the Internet, a person purporting to be Zarqawi on Friday threatened more bombings and bloodshed in Iraq and said US President George W. Bush would not be allowed to ?enjoy peace of mind?.

In a reminder of the huge security challenge ahead, US Marines and Iraqi forces are having to use heavy machinery to remove vast amounts of arms and ammunition found in a guerrilla supply corridor between Falluja and another rebel stronghold at Ramadi, the military said.

Weapons collected so far include nearly 38,000 high-velocity bullets, 180 artillery shells, more than 4,000 mortar rounds and 600 grenades, the military said. Those are the types of arms commonly used by insurgents in their bid to topple Iraq?s first democratically elected administration in half a century, and drive out US forces.

<B>Lutfi ABU OUN</B>