The attack appeared aimed not at seizing parts of the Iraqi capital but rather at showing the Iraqi people that President Saddam Hussein no longer enjoyed absolute power.

After the incursion the commander of the US-led air campaign against Iraq proclaimed that the Iraqi military no longer exists as an organized fighting force.

“The Iraqi military as an organized defense in large combat formations doesn’t really exist anymore,” Lt. Gen. T. Michael Moseley said in a telephone press conference with reporters.

Saddam responded to the military offensive by urging Iraqis to attack US and British forces across the country to relieve pressure on the besieged capital, in a speech read on state television by Information Minister Mohammed Saeed Al-Sahaf.

“The enemy has concentrated all its forces against Baghdad, which has weakened its power in other parts of Iraq... You must now weaken them, deepen their wounds and deprive them of what they have taken of your land,” the minister quoted Saddam as saying.

But US President George W. Bush used his Saturday radio address to praise the US/UK troops and insist that the United States was bringing “liberation” and “hope” to the Iraqi people.

In London, a Downing Street spokesman said units of Iraq’s elite Republican Guards had suffered a “comprehensive defeat with very heavy losses” as US tanks rolled into this city. The US battalion moved into Baghdad from the capital’s Saddam International Airport after US commanders seized control of the airport and renamed it Baghdad International Airport.

A defiant Al-Sahaf claimed the coalition troops had been chased out of the airport: “We have defeated them. In fact we have crushed them. We have pushed them outside the whole area of the airport.”

But a US military spokesman scoffed at that claim, saying the only Iraqi troops he had seen at the airport were “dead or captured.” US Maj. Gen. Victor Renuart, speaking in Qatar, said US forces could now enter the capital at will. “We can move at times and places of our choosing,” he told reporters at US Central Command in Qatar.

However, he acknowledged that “the fight is far from over in Baghdad”.

A US commander said around 1,000 Iraqi troops had been killed in the drive into Baghdad and a reporter saw dozens of Iraqi military vehicles burning in the streets.

Infantry commander Col. David Perkins said Iraqi bodies were “all over the streets”, after US troops in and around the city engaged in the fiercest fighting since the war began on March 20.

Surprised Iraqi forces, including members of the Republican Guards and the ruling Baath Party, put up fierce resistance, mostly with AK-47 rifles and rocket-propelled grenades (RPGs), according to accounts by officers and soldiers.

Although it was not the house-to-house fighting that some analysts fear could yet bog down US forces, it was particularly violent and occurred in residential and business districts. Soldiers said they knew of no civilian casualties, adding that they refrained from using heavy fire when they feared civilians were nearby.

A US tank commander was shot and killed and two other soldiers were wounded during the operation, a senior officer said.

“This wasn’t a patrol — go in and come out,” Navy Capt. Frank Thorp said at US Central Command in Qatar. He later told a reporter: “We have coalition armored combat formations right in the heart of Baghdad.”

However there were no signs of a US military presence in the capital later yesterday. The city seemed strangely normal, with Baghdadis out and about and cars and buses on the roads. Soldiers, members of the elite Republican Guards and militiamen were posted at a major intersection leading out of the city but appeared as steely-nerved as ever.

The ground incursion came after US and British forces launched a night of heavy raids on the city, with fireballs lighting the night sky and warplanes roaring overhead.

Col. Perkins said the US forces had destroyed about 100 pieces of Iraqi equipment, including air defense systems, tanks, rocket-propelled grenade launchers, recoilless rifles and guided anti-tank missiles.

Army Specialist Joshua Kinnison, his face smudged with dirt, said he was physically drained from the fight.

Iraqi fighters were “lying all over the side of the road. I can’t even count how many. They were everywhere,” he said.

US infantry commander Col. Will Grimsley said the dawn tank raid into this city was a case of “let me poke you in the eye because we can and you can’t do anything about it”.

Further to the southwest, the US 101st Airborne Division launched an air assault to secure the central town of Karbala, less than 100 kilometers from here.

Maj. Mike Slocum, the 101st Aviation Brigade’s watch officer, said helicopters had transported more than a battalion of soldiers into the outskirts of Karbala. “Basically they are on the ground to go through and secure the highways and supply routes and also they are looking to squelch any paramilitary threat in the area,” he said.

British forces in the south found 200 coffins containing human remains stashed in bags at an abandoned military base near Al Zubayr, 20 kilometers from the strategic southern city of Basra.