Dubai: Tightening their hold, the invading US troops backed by artillery and mortar fire on April 3 advanced to within 15 kms of downtown Baghdad and were preparing to seize the airport in a "decisive phase" of the war on Iraq, which has entered the third week.

Amid reports that Iraq's Republican Guards were moving South of the capital to defend it, troops of the 3rd Infantry Division have controlled a key intersection South of Baghdad and were 15 kms away from the city centre.

British forces battling to take control of the Southern city of Basra were still facing resistance from about 1,000 Iraqi militia along with regular troops, according to a British military spokesman.

US forces said they are taking up positions outside Baghdad international airport, which is about 20 kms from the city centre, and are preparing to capture it.

The US military officials said US spy planes spotted an unspecified number of Republican Guard soldiers moving in the direction of the airport.

Coalition commanders spoke of the war entering a "decisive phase". The Iraqi regime has "a dagger at its heart", said one commander.

However, the fact that US forces have encountered relatively little resistance during their approach towards Baghdad has raised some fears that they may be being drawn into a trap.

As the coalition forces converge in the region and resistance fails to materialise, they are worried that they could come under chemical attack.

US forces on April 2 surged past the towns of Karbala and Kut and captured key bridges over the Euphrates and Tigris rivers.

Iraqi leader Saddam Hussein vowed his troops would repel the invading army. "They will not let them reach Baghdad," Saddam said in a letter to his niece, read on the state television on April 2 night.

"They will cripple them until they return to their countries defeated, leaving our country for its people."

Iraqi television also showed footage of Saddam Hussein smiling and laughing with members of his Cabinet. However, it is not clear when the pictures were taken.

A US Army Black Hawk helicopter was shot down in Southern Iraq, killing seven of the 11 soldiers aboard, Pentagon officials said, adding the other four soldiers on board were wounded and have been rescued.

A single-seat US fighter jet was also missing over Iraq, presumed to have been shot down by a surface-to-air missile. There is no word yet on the fate of the pilot.

Raids by US B-52 bombers on tanks defending Baghdad included the use of highly controversial cluster bombs. The 454-kg CBU-105 bombs each contain 10 armour-destroying bomblets, the US military said.

The British military has also said it is using cluster bombs on the outskirts of the Southern city of Basra.

US military said it had destroyed two divisions of the Republican Guard in head-to-head combat South of the city on April 2, but Iraq has dismissed the claims as "lies".

Iraqi television carried comments by the commander of the Baghdad division – which US says it destroyed – saying only 17 of his men had been killed and 35 wounded.

Reports from the war zone said Kurdish fighters backed by US planes clashed with Iraqi forces for control of an army command headquarters in Khazer on the road to the Northern city of Mosul.

An Iraqi hospital source said eight civilians were killed and five were wounded by a missile that hit a vegetable market at Nahrawan on the South Eastern edge of Baghdad.

A US officer claimed that about 500 Iraqi troops were killed as American forces repelled the Iraqi bid to take back a key bridge some 30 km South West of Baghdad.

As the ground forces fought from the South, the aerial bombing in and around Baghdad continued. More explosions were heard across the city coming from the Southern and South Eastern fringes of the capital.

Iraq's Information Minister Mohammad Saeed al-Sahhaf accused the US-led forces of bombing mosques and trying to destroy sacred sites in Karbala and the Central city of Najaf.

The US military denied it had struck a mosque in Najaf, and accused Saddam's forces of being behind any damage to protected sites there.

PTI