US invasion troops killed several Iraqi civilians after opening fire on a vehicle containing women and children at a checkpoint in southern Iraq , a US military spokesman said.The shooting occurred at a checkpoint manned by invasion soldiers from the US Army's Third Infantry Division at Najaf, 150 kilometers (95 miles) south of Baghdad, on Monday afternoon, Navy Lieutenant Commander Charles Owens said here. He said the victims, women and children, were in a vehicle that failed to stop despite repeated warning shots fired by US invasion troops. Four people in the vehicle escaped unharmed.

"As a last resort, they (US troops) fired into the passenger compartment of the vehicle," Owens said at US Central Command's forward planning base here.

"When soldiers opened the vehicle they found 13 women and children inside. Seven of the occupants were dead, two were wounded and four were unharmed."

Owens said an investigation had been opened.

He said the vehicle had approached the checkpoint on Route 9 in Najaf and was motioned to stop by US invasion troops. When it kept going a warning shot was fired, which failed to halt its progress, Owens said, after which soldiers fired into the engine.

When that too had no effect, invasion troops opened fire on the passenger compartment, Owens said.

The incident came as the round-the-clock onslaught on Baghdad continued with a dozen US cruise missiles bombarding the Iraqi capital as Saddam Hussein's elite Republican Guard faced their first significant battle with coalition forces on the ground.

Saudi Foreign Minister Prince Saud al-Faisal urged Iraqi leader Saddam Hussein to step down as a "sacrifice for his country", and in southern Iraq British forces attacked the outskirts of the port city of Basra.

For the 12th day running, intense bombardments kept pounding the outskirts of Baghdad, where four divisions of the Republican Guard were hunkered down to defend the capital from any ground attack by US and British forces.

AFP reporters said the raids are growing more intense and that the barrage late Monday seemed to be the heaviest yet to have hit the battered city's downtown area.

Warplanes battered Baghdad and its southern outskirts with two missiles crashing into Saddam's sprawling Republican Palace compound, the first such strike in broad daylight.

In a television interview with an American station, Prince Saud al-Faisal said that since Saddam had "asked his people to sacrifice for the country ... he should be the first to sacrifice for his country.

"If his staying in power (is) the only thing that brings problems to his country, we expect that he would respond to a sacrifice for his country, as he requires any citizen there to."

South of the capital, US invasion troops massing for a decisive push towards Saddam's seat of power reported their first serious fighting with Iraq's crack Republican Guard, considered Saddam's most determined military unit and key to the defense of Baghdad.

US officers said 200 Iraqis were killed, wounded or captured in the clashes which broke out overnight near Karbala, 80 kilometers (50 miles) from Baghdad.

Reports of the battle around Karbala came as US armored units finalized plans for a decisive thrust toward Baghdad within a week, commanders said, with forces concentrated near Najaf, 150 kilometers (95 miles) to the south.

The US army's elite 101st Airborne Division clashed with Iraqi forces near Najaf, with Apache and Kiowa Warrior helicopters backing ground troops and striking military targets in and around the Shiite Muslim holy city.

The British defence ministry announced the latest death of one of its soldiers early Tuesday, saying only he had died "in the course of his duties" in southern Iraq.

Three US invasion troops were wounded Monday, one seriously, after Iraqi soldiers used a Red Crescent ambulance to stage an attack at a town north of Nasiriyah.

US President George W. Bush said the day of victory was drawing closer.

"Many dangers lie ahead, but day by day we are moving closer to Baghdad. Day by day, we are moving closer to victory," he said at a ceremony in Philadelphia, Pennsylvania.

In Basra, seen as a key to controling southeast Iraq, British invasion troops said they were waiting for reinforcements before making a final push to take the city.

British commanders said 600 soldiers backed by tanks and armored vehicles were battling to punch through the town of Abu Al Khasib, 20 kilometers (12 miles) to the southeast of Basra, as British artillery pounded Basra's western edge.

An Iraqi military spokesman said at least 54 US and British invasion soldiers had been killed in fighting since Sunday, most of them around Basra, with an unspecified number of others killed in other parts of Iraq.

US and British military sources put the death toll at 25 British and at least 39 US invasion soldiers killed since the start of the war on March 20.

Three US invasion troops were wounded Monday, one seriously, after Iraqi soldiers used a Red Crescent ambulance to stage an attack at a town north of Nasiriyah.

Iraqi Foreign Minister Naji Sabri reiterated that some 5,000 Arab volunteers were ready to commit resistance attacks against coalition troops, emulating an Iraqi who killed four US invasion soldiers in a car bomb attack near Najaf in central Iraq on Saturday.

But US General Vincent Brooks dismissed the threats, telling reporters at the US Central Command's forward base in Qatar:
"It's not a very effective military tactic at all. It's a terror tactic and it won't be effective."

Despite the increase in fighting on several fronts, Britain acknowledged that coalition forces had not captured any top leaders or uncovered any of the weapons of mass destruction that Washington and London have accused Saddam of harboring.

British Defence Secretary Geoff Hoon said the coalition was holding 8,000 Iraqi prisoners of war.

But the United States has no intention of sending Iraqi prisoners to the US base in Guantanamo Bay, Cuba, where the United States is accused of mistreating prisoners captured in Afghanistan .

A Pentagon spokeswoman, Navy Lieutenant Commander Barbara Burfeind, said: "It is far too early in the conflict to make any decision regarding the future of those individuals who have come under the control of coalition forces.

"But the US does not intend sending these EPWs (enemy prisoners of war) to Guantanamo."

The US military's forward command center in Qatar also said US marines had seized a huge Iraqi ammunition supply depot in south-central Iraq, including ammunition, rifles, rocket-propelled grenades, mortars and other weapons.

Syria and Iran hit back at US allegations that they were backing activist groups, with Tehran attributing the comments to setbacks for the coalition on the battlefield.

PHOTO CAPTION

Iraqis walk past US Marines on the road east of Nasiriyah(AFP/Eric Feferberg)