Saddam Hussein's regime showed no sign of surrender, with battles raging in Baghdad as US troops surrounded part of the city, the centre of which saw its first rocket and mortar fire in 18 days of war. Heavy exchanges of fire in southern Baghdad intensified in the evening, with artillery, mortar and rocket blasts and machine-gun fire heard loudly from the center of the capital, AFP correspondents said.

The firing, which began three hours earlier, seemed to intensify around 9:30 pm (1730 GMT) in the south and southeast of Baghdad.

Anti-aircraft batteries lit up the sky, which had been almost completely dark due to a power cut.

Loud explosions again rocked the capital of five million, as warplanes roared overhead and ambulance sirens wailed.

It was the first day mortar and rocket fire had been heard in Baghdad, whose airport US forces captured Friday.

US Army troops circling Baghdad fought their way north during the day, killing or wounding hundreds of Iraqi soldiers and inflicting major damage to their equipment, a US military official said.

Major Ross Coffman said the soldiers of the 3rd Infantry Division completed the western portion of a planned encirclement of Baghdad and were waiting for US Marines to close the door from the east.

Coffman said soldiers, backed by close air support, destroyed an Iraqi tank battalion, leaving hundreds of Iraqis dead or wounded.

The Iraqis lost 23 tanks, 22 artillery pieces, 10 anti-aircraft batteries, three ammunition storage sites, four multi-launch rocket systems, 26 trucks and 30 armored personnel carriers, according to Major Mike Birmingham, the 3rd Infantry's public affairs officer.

After completing a 70-kilometer (43-mile) push, the army controlled a semi-circle around Baghdad extending from the Tigris in the north to where the river leaves the capital in the south, the major said.

Heavy Iraqi Deployment in All Baghdad Neighborhoods

Armed Iraqi paramilitary troops and policemen were heavily deployed in all Baghdad neighborhoods, with more trenches being dug along main roadways.

An AFP reporter who made a tour of southern Baghdad in the afternoon said the streets there were completely empty except for clusters of heavily armed soldiers and activists from the ruling Baath party at street corners, roundabouts and main roadways.

Travel Ban Alarms Baghdad's Residents

Earlier Sunday, about a dozen mortar bombs had struck in the busy Saadun commercial area in the heart of Baghdad and multiple rocket fire, sounding like Russian-made Katyushas, was heard by AFP correspondents in the city.

But Baghdad's residents, many of whom have moved to the countryside or with relatives in the city center that they perceive as less vulnerable to attack than the outskirts, seemed to be even more alarmed by a new 12-hour travel ban to and from their capital starting at 6:00 pm (1400 GMT) each evening.

Information Minister Mohammed Said al-Sahhaf told reporters the measure was decided in order "to prepare our movements and our work to confront the enemy and crush him."

Sahhaf, like all Saddam's officials, insisted Sunday US forces did not control the airport and that Iraqi attacks since Saturday had "killed 50 soldiers in enemy ranks."

PHOTO CAPTION

Smoke billows from heavy shelling on a residential area in central Baghdad. The US-led war on Iraq has entered it's 17th day, with US troops massing on the southern edge of Baghdad, according to US military officials. (AFP/Ramzi Haidar)