"An incident has occurred involving a group of British light armoured vehicules belonging to D squadron of the Blue and Royals of the assault cavalry regiment," a spokesman said of the incident, which took place Friday.

"One British soldier is missing believed killed and four others injured. The incident is currently being investigated," he told AFP.

"There is a suggestion that this was a blue on blue incident," he added, using the military term for a friendly fire incident.

Britain's Press Association (PA), quoting a senior defense official, reported earlier that one person had died and three were injured in an attack in southern Iraq.

PA said the soldier was killed after an American A10 tankbuster plane targeted two armored vehicles near Iraq's second largest city Basra.

The spokesman for the ministry of defense refused to confirm that information, but said it was being investigated.

"The suggestion that an american aircraft was involved is obviously one of the things that we are investigating," he said.

The incident brings to five the number of British soldiers who have been killed by friendly fire since the US-led war on Iraq began on March 20.

On March 23, a US anti-missile Patriot missile shot down a British Tornado bomber, killing both pilots on board.

On March 24, two soldiers were killed when a British Challenger tank mistakenly opened fire on another Challenger tank.

A total of 23 British soldiers have so far died in the conflict, including 14 as a result of helicopter accidents and four killed in action. That toll already exceeds that of the 1991 Gulf War by five -- then 18 British soldiers died, nine of them by friendly fire.

Separately, the Daily Mirror reported Saturday that the number of British troops serving in the Gulf could be cut dramatically from 45,000 to 5,000 if the US-led war against Iraq drags on for at least six months.

"Because of the massive pressures on our boys all over the world we will have to consider our commitment in the Gulf very carefully over the coming weeks," the Daily Mirror quoted a senior government official as saying.

Britain and Australia are the main contributors of troops to the war alongside the United States, which began fighting to oust President Saddam Hussein and wipe out his alleged weapons of mass destruction program on March

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