A SECOND British soldier has died in action in the Gulf. The man, from the 1st Battalion of the Black Watch, was killed during an operation last night near Al Zubayr, south west of Basra.

The news came as American air forces were today pounding Iraq's Republican Guard south of Baghdad as their ground troops closed in on the capital.

Reports claimed Saddam Hussein had authorised the use of chemical weapons if other defences failed before Baghdad.

Also the first British soldier killed in action in the Gulf was named today as Sergeant Steven Mark Roberts, 33, of the 2nd Royal Tank Regiment, who was shot at Al Zubayr near Basra on Sunday and died yesterday. He was married with a child and from Bradford.

The air attack on Saddam's elite troops was being carried out by Apache helicopters flying constant sorties, while giant B52 bombers were also hammering their positions.

American press reports say intelligence sources are suggesting that Saddam Hussein has given the go-ahead for chemical weapons to be used if the Republican Guards are unable to hold their attackers off by other means.

The US aircraft were said to be targeting the Republican Guard's Medina Division, one of two guards' divisions believed to be standing between Baghdad and the rapidly approaching US forces.

The likely clash with the Medina Division was highlighted by Tony Blair in the House of Commons yesterday . "This will plainly be a crucial moment," he said.

American officials say Mr Blair is due to meet President George W Bush in the United States tomorrow (wed) for talks about the war's progress.

Although US commander General Tommy Franks said his forces had made rapid progress, with US marines only 60 miles from Baghdad earlier today, there are still concerns about pockets of resistance being met in the south of Iraq, with ten US troops having been killed in fighting around Nasiriyah.

There are also fears that British troops may have to engage in street fighting in Iraq's second city of Basra, particularly if humanitarian aid is to be brought into the area quickly to avoid a potential human catastrophe there.

British military sources said they hoped the first aid shipment to Iraq would arrive within the next two days American opinion was again outraged when more captured US servicemen - in this case the two-man crew of a downed Apache helicopter - were shown on Iraqi television.

Kurds in northern Iraq are said to have fled their homes to take refuge in caves, fearing the use of chemical weapons against them.

Meanwhile President Bush is set to ask Congress for $75 billion (£47 billion) to pay for the war and other security measures.

Public support for the conflict is said to be growing in Britain, but 21 Arab countries have condemned the invasion, and senior Labour Party members are set to discuss a motion questioning its legality.