Coalition troops may be in Baghdad "within three or four days", a spokesman for British forces in the Gulf said today.

He was commenting as tanks from the US 7th Cavalry sped towards the Iraqi capital meeting little resistance.

In the south of Iraq, allied forces were continuing to consolidate gains made overnight after the launch of the ground invasion.

Royal Marines seized oil facilities in the Al Faw peninsula and US Marines raised the US flag over the key southern Iraqi port of Umm Qasr after overcoming only light resistance, according to reports.

Group Captain Al Lockwood, a British military spokesman, told reporters at the main allied command centre in Qatar that he believed coalition forces could be in the Iraqi capital in as little as three days.

He said: "If I was a betting man, and I'm not, I would say hopefully within the next three or four days."

Royal Marines commandos stormed the Al Faw peninsula to capture key oil facilities last night.

Their lightning offensive began at about 7.25pm UK time with heavy artillery shelling before elite troops stormed numerous installations.

Six Iraqis were said to have been killed, 16 captured and one vehicle destroyed but there were no reports of any US or British casualties.

Some parts of the Al Faw complex had been set alight, but Group Capt Lockwood said they had secured the oil facilities and were now moving up the peninsula.

The troops met only "light resistance" and suffered no casualties, he said, adding: "They have secured the beachhead and moved up along the peninsula to secure the oil infrastructure."

Scores of Iraqi soldiers surrendered, raising hopes that Iraqis all over the country will follow suit.

Royal Marines securing oil installations at the peninsular encountered the troops at around 5.30am.

BBC correspondent Clive Myrie witnessed about 60 Iraqis emerge from their bunker positions with their hands up, waving white flags, before getting on their knees ready to be taken as prisoners of war by Royal Marines from the 40 Commando.

A makeshift detention centre will now be set up in the area where the prisoners will be given food, shelter and medical assistance.

It had been feared Iraqi troops at Al Faw, just south of the city of Basra, would blow up the oil installations before either resisting or retreating.

Ecologically, this would have been disastrous as the waterways that flow from Al Faw would have carried oil and debris into the Arabian Gulf.

Elsewhere, in a possible sign that Baghdad was about to face further attacks, a wave US B-52 bombers took off from RAF Fairford this morning.

The Gloucestershire-based bombers have yet to see action in the war against Saddam Hussein.

On the ground, the 7th US Cavalry in Abrams main battle tanks and Bradley personnel carriers were "charging to Baghdad", in the words of CNN TV reporter Walter Rodgers, who is travelling with them.

After an initial skirmish with Iraqi troops when they burst out of Kuwait, the Apache and Crazy Horse troops of the cavalry raced across the desert at 25mph for hours without meeting any opposition.

Waiting to follow them was the 3rd Infantry Division.

However, Rodgers said the US troops were "realistic" that they would have to fight nearer to Baghdad, particularly the Iraqi Republican Guard.

The apparent ease of their passage so far had been the "lull before the storm", he said, adding: "Every soldier knows the way they're heading and their objectives and there will be a hard fight ahead."

In a separate offensive to the west of Basra, troops from the 7th Parachute Regiment Royal Horse Artillery helped US soldiers securing oilfields from possible sabotage.

Coalition forces in northern Kuwait carried out a heavy bombardment of the area around Umm Qasr before today's breakthrough.

Securing the port should set the stage for the capture of Basra, which lies just 20 miles from the Kuwait border.

Some units in southern Iraq, such as the 1st Marine Expeditionary Force, have already met resistance.

The troops were pinned down by Iraqi anti-tank rockets and small arms fire just yards after crossing the border, according to BBC News 24's correspondent Adam Mynott.

He said the convoy he was in had been forced to retreat and it was unclear whether one vehicle had been hit. British artillery fire had been called in.

"We're now taking cover behind a sand bank," he said.

"There is sustained gunfire coming from Iraqi positions. Resistance is stronger than had been expected."

But hundreds of Iraqis have been surrendering.

The US 15th Marine Expeditionary Force advancing in southern Iraq today encountered 200 or more Iraqi troops seeking to surrender.

One group of 40 Iraqis marched down a two-lane road towards the Americans and gave up.

They were told to lie face down on the ground before being searched.

On the political front European leaders today expressed personal condolences to Tony Blair today over last night's helicopter crash in Kuwait - but French President Chirac was not among them.

German Chancellor Gerhard Schroeder, Irish premier Bertie Ahern and Spain's Jose Marie Aznar went over to Mr Blair at the start of the second day of an European Union summit in Brussels.

Italy's Silvio Berlusconi, Dutch leader Jan-Peter Balkenende, and Denmark's Anders Fogh Rassmussen did the same.

"They all offered their personal condolences before the meeting happened," said a Government spokesman.

Asked if French President Jacques Chirac had done the same, the spokesman replied: "The French President was late for the start of the meeting."

Iraq in depth: iraq.usatoday.com