The morning incursion into the heart of the city sent pick-up trucks loaded with nervous Kalashnikov-toting militiamen speeding along the deserted main roads.

Clusters of unshaven men in military fatigues and civilian clothing, ammunition strapped across their chests, stationed themselves behind sandbags, walls and trees along the roads, as military jeeps on street corners kept their mounted anti-aircraft guns pointed horizontally.

The heart of the capital stank of sulphur and sporadic fire could still be heard coming from the Republican Palace, Saddam's seat of power along the west bank of the Tigris river in the Al-Karkh district, hours after the raid that woke up residents.

But at midday, there was no sign of the US forces seen at the start of the assault on the compound and other key sites of Saddam's regime which the US-British coalition later claimed to have seized in what a spokesman called "an armoured raid through the city."

During the battle for the palace, an arms depot on the riverside caught fire and thick white smoke engulfed the compound, worsening air already polluted by a sandstorm and black smoke belching out of burning fuel trenches.

US troops were met with fierce resistance at the compound where dozens of Iraqi elite troops wearing black were seen running along a bank and entering one of the main buildings.

Access to the gigantic gates of the presidential compound, already battered by weeks of coalition air strikes, had been blocked by armed militiamen manning checkpoints on nearby streets.

The administrative district around the compound, including the ministries of information and foreign affairs, was still in Iraqi hands in the early afternoon.

The road leading from the information ministry toward the foreign ministry was manned by armed soldiers in full gear and paramilitary troops, clad in military fatigues and red keffiyeh headdresses.

Armed militiamen stood guard behind sandbags at the entrances of the ministries and other nearby official buildings, including the presidential construction agency and the Baghdad Security Directorate, which has been destroyed by US missiles.

Access to the nearby Al-Rashid hotel, one of the capital's main landmarks and which was rumored to have been seized by US troops, was also prohibited.

Ambulance sirens wailed across the city, and the central Al-Kindi hospital said it had admitted three dead and 50 wounded.

Also on the Al-Karkh bank, hundreds of civilians pressed in vain at the gates of Al-Alawi bus station.

"All these people came here because they wanted to leave town, but there are no buses," said a doctor from Al-Rashid military hospital trying to travel to his home in Al-Faluja, 30 kilometres (20 miles) west of Baghdad.

The civilians tried to flag down the odd passing private car in the hope of hitching a ride home or out of the besieged city.

"I did not know there was an attack. I was caught up in the battle," said the doctor, explaining he had just come off a night shift.

"Eighty percent of the hospital beds are taken by people suffering from war injuries," he said.

On the eastern Al-Rusafa bank of the Tigris, traffic was also slow but small neighborhood cafes were still full of people, grocery shops were open, fruit stalls erected and street vendors hawking cigarettes stood on main roundabouts.

But civilians trying to cross the river by the Al-Jumhuriya bridge, close to the palace compound, were stopped by armed militiamen who did, however, allow military vehicles to cross.

Shutters were firmly down over shop windows along the Al-Mansur commercial avenue in Al-Karkh. Outside one shop, a group of children sat looking at a giant statue of Saddam Hussein pointing in the direction of Jerusalem.

SPACE.WIRE