The commander of the 101st Airborne Divsion's Aviation Brigade, Colonel Greg Gass, told AFP US infantry, tanks and helicopters had met strong resistance in the city over the past three days but Iraqi soldiers now appeared to have given up their defence posts.

"I know they (US forces) have made quite a bit of headway in the past several days and it is coming very close to being secure," Gass said.

"It's a matter of days before it will be secure."

Gass said the US forces had seen a drastic drop in Iraqi resistance from within Najaf on Tuesday, one of many signs that indicated they were close to controlling the city.

"It looked like most of the equipment had been abandoned -- air defence systems, military trucks and vehicles," Gass said.

"Their (military) compounds had no people in there."

US forces also secured Najaf's single strip airfield just south of the city late on Monday.

Two 101st Black Hawk helicopters were the first US aircraft to land on the airstrip on Tuesday, flying in small amounts of humanitarian aid as an initial step to try to win over the local Muslim Shiite population and undermine Iraqi resistance.

Najaf, 160 kilometres (100 miles) southwest of Baghdad, is a key city in the US military push towards Baghdad because control of it would allow smoother supply and communication lines.

Gass said an equally important reason for controlling Najaf was because the city was a base for Iraqi military operations in central and southwest Iraq.

He said the 101st had been heavily involved in the Najaf campaign, sending infantry troops as well as Kiowa Warrior and Apache helicopters, with the 3rd Infantry Division supplying mechanised and armoured support.

Gass earlier described the combat around Najaf on Sunday and Monday as the heaviest his forces had been involved in since the start of the war on March 20

And a statement from US Central Command's headquarters in Qatar on Tuesday said that several Iraqis had been killed near Najaf the previous day.

"The 101st Air Assault Division conducted aggressive patrols northwest and south of Najaf, which resulted in the capture or defeat of one 120mm mortar, four weapons caches, several enemy KIAs (killed in action) and approximately 20 enemy prisoners of war," the statement said.

The Black Hawk helicopters delivered 760 litres of bottled water and 580 ready-to-eat meals to civilians in Najaf in what the pilots said they hoped would be the first of many such humanitarian flights.

"We're just giving them food and water and hoping that our help wins over some of the Shiites," one of the pilots, Captain Eric Then, told AFP correspondents allowed on the flight.

Najaf and Karbala, 80 kilometres closer to Baghdad, are important holy cities for the Shiites, who make up 60 percent of Iraq's population but have been generally oppressed by the minority Sunni Muslims who dominate Saddam's regime.

The focus on providing food, water and medical supplies in the wake of the invading US and British forces is designed to reinforce the Anglo-American message that their soldiers are attacking only the regime of Iraqi President Saddam Hussein and want to help ordinary Iraqis.

But the humanitarian mission to Najaf paled in comparison to an incident on Monday when US soldiers manning a checkpoint close to the city shot up a civilian vehicle that failed to stop on their command, killing at least seven women and children.

SPACE.WIRE