Coalition aircraft pounded a convoy of Iraqi tanks and armored vehicles streaming out of the besieged southern city of Basra late Wednesday, British military sources said.

The sources estimated the column at about 120 vehicles, heading southeast along the main road toward Abadan. They said it appeared the Iraqis were using the sandstorm that had blanketed the region to try to sneak out.

British forces have ringed Basra for several days, exchanging artillery fire with forces loyal to Saddam Hussein's regime. The British say they are coming to the defense of inhabitants who rose up in the streets against Saddam Hussein's regime on Tuesday.

Basra had been largely quiet Wednesday, after British forces "neutralized" militia fighters who had lobbed mortars at Basra's residents on Tuesday, said Lt. Col. Ronnie McCourt, a spokesman for British forces in the Gulf.

British Prime Minister Tony Blair, speaking in Parliament on Wednesday, promised backing for the insurgents.

"Truthfully, the reports are confused, but we believe there was some limited form of uprising," Blair said. "It is important that we give support to those people in Iraq who are rising up to overthrow Saddam and his deeply repressive regime."

Iraq has denied there was an uprising in Basra.

The unrest came as the British tried to gain control of Basra and relieve the city's trapped civilian population of 1.3 million, which was running out of food and drinking water.

Coalition forces have made no secret of their hopes to spur such uprisings in the strategic southern city.

"We are assessing the situation very carefully to see how we can capitalize on it and how we can assist," said Group Capt. Al Lockwood, a British spokesman.

U.S. warplanes had dropped satellite-guided bombs on central Basra, targeting military sites hidden in civilian buildings, according to British accounts. The Baath Party headquarters was destroyed.

"The bunch of desperadoes who've lived above the law rule the roost in this dictatorship, this regime that Saddam Hussein has been running," McCourt said.

"They're obviously resorting to desperate measures and trying to intimidate the population, and we are making certain that we neutralize them as quickly as possible."

Britain's 7th Armored Brigade -- the famed Desert Rats -- was deployed on the edge of the city.

"We're not going in. We wait for them to come to us. Where we get targets of opportunity, we take it," according to a British military official in Kuwait.

Coalition forces had avoided entering Basra for fear of getting bogged down in urban warfare. But they changed their strategy because of concerns for civilians and tenacious resistance in the city from an estimated 1,000 militia fighters and an unknown number of regular troops.

During the 1991 Gulf War, Basra's Shiites rose up against Saddam's Sunni Muslim regime. Government forces crushed the rebellion, slaughtering thousands across the south.

On Tuesday night, thousands of Basra residents rampaged through the streets and set dozens of buildings ablaze, according to British reporters attached to military units.

"It appeared some of the population rose up and started attacking elements that are defending the city. These elements more and more as we're investigating them appear to be mostly criminal elements and ruling Baath party members," Lockwood said. "The attack from the local population obviously gave them cause for concern to the extent that they started mortaring them."

On Wednesday, McCourt said British forces were trying to prevent "these thugs and hoodlums" from trying to slip out of the city.

The city's electricity was knocked out Friday during U.S.-British bombing. That in turn shut down Basra's water pumping and treatment plants. The U.N. Children's Fund estimated up to 100,000 Basra children under age 5 were at immediate risk of severe disease.