Air Marshal Brian Burridge, the commander of British forces in the Gulf, said the tanks were attacked Wednesday evening after the column left Basra and headed southwest towards British forces occupying positions in the Fao peninsula.

"Having established they were not trying to surrender, UK forces took swift and decisive action against this threat destroying a number through a mixture of artillery and coalition air power," Burridge told journalists at Central Command headquarters in Qatar, without giving further details.

According to a journalist embedded with a British unit close to Basra, the column was made up of some 120 Soviet-built T-55 tanks.

Burridge said the column's movement did not appear to be part of a coordinated counter-attack by Iraqi troops in Basra, the country's second city and a key port with 1.2 million inhabitants.

Instead he suggested that forces from Iraqi President Saddam Hussein's Baath Party had rounded up troops and forced them into the tanks.

"Picture the scene: These militias, probably Baath Party militia, go through a neighbourhood, round up existing soldiery, put them in tanks and say, 'Go that way,'" said the commander.

"I'm not convinced that there is ... a division moving anywhere," he said.

"You can tell from the way they are dispossessed operationally that this is not a fighting formation that really knows its business. It is disorganised but there is someone in there trying to organise it."

British forces Wednesday entered the outskirts of Basra amid the reports of an attempted rebellion by local Shiite Muslims against the mainly Sunni-led regime of President Saddam Hussein.

A day earlier, British officers said they had fired on Iraqi forces inside the city who had been shooting at locals in a bid to quell any uprising.

Burridge said the situation in mainly Shiite Basra remained "ambiguous" but it appeared that some civilians had turned on Saddam's ruling Baath party.

"Probably someone the Baath Party was trying to intimidate was not going to be intimidated so they shot 'em and that's the way of these things in counter-insurgency warfare.

"That tends to be the way these things start to get unhinged because someone develops either the courage or the recklessness occasionally to fight back, saying I'm not going to put up with this."

As ground troops waited on the edge of the city, two British Harrier jets used satellite-guided bombs to obliterate the Basra headquarters of the Baath Party, British commanders said.

"It was a way of saying to the rioters on the streets of Basra that the Baath Party is not a threat to them any more," said Wing Commander Andy Suddards, the officer commanding the raid.

Desert Rat units from the British 7th Armoured Brigade were manoeuvring to the north of the city and conducting search and destroy patrols to hunt down Iraqi forces trying to enter or flee.

Washington encouraged Shiites in Basra to revolt against Saddam after the 1991 Gulf War but failed to back them with military support. Many were slaughtered in the ensuing crackdown.

In the latest war, hardline Iraqi troops including irregular Fedayeen volunteer militia have been sent to the town to stiffen defences and keep the locals under control.

Baghdad has vehemently dismissed the claims of a revolt as US "lies" aimed at demoralising the Iraqi people.

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WAR.WIRE