Abductors of Iraq Britons 'want snatched sheik to be released'

Among them is said to be Sheik Aws al-Khafaji, a key ally of radical cleric Moqtada al-Sadr, who was arrest by British troops in Basra two weeks ago.

Iraqi government sources said that a demand had been received from an "element" purporting to be within Sadr's Mahdi Army.

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The British computer specialist and his four bodyguards were seized in carefully planned operation by men dressed in police and commando uniforms from the finance ministry on Tuesday.

One of the Britons was named yesterday as father-of-one Alex MacLachlan, 28, a former soldier, from South Wales. The other four are still unidentified.

His distraught mother Helen said: "We are just so upset and shocked - we just want to know our son is safe."

Mrs MacLachlan and her husband Colin are in contact with the Canadian security firm GardaWorld, which employed the bodyguards.

However, she added: "We don't know anything more other than what we see on the television and in the news."

The couple's other son, Ross, 30, is serving in Kuwait and has been told he can return home to comfort the family.

The British Embassy in Baghdad issued a travel advisory warning British nationals, including security contractors, that "further kidnaps may be planned".

In what is apparently their first communication, the kidnappers are said to have stressed that the Britons were unharmed and to have named at least three men close to Sadr in their demands, including one of his spokesmen arrested by U.S. forces in Baghdad.

The Foreign Office said it was unaware of any demands and it was continuing to work with the Iraqi authorities to identify the kidnappers and secure the men's release.

Sadr has made no public comment on the abductions, but his aides claimed the operation was beyond the capability of the Mahdi Army.

U.S. and Iraqi forces have carried out raids in the Sadr City area of Baghdad in their hunt for the Britons, using armoured vehicles to smash down walls of houses.

The unusually heavy-handed tactics indicate the soldiers are racing to find them before they are moved, possibly out of the capital.

The SAS is on standby for a rescue while hostage negotiators have flown into Baghdad to secure the release of the Britons, who appeared to have been specifically targeted.

Sadr City, the Mahdi Army's Baghdad heartland, is close to the finance ministry where the men were seized.