"We can confirm that there is an incident apparently involving friendly fire and we are investigating as a matter of urgency," a defence ministry spokesman told AFP.

"The detail of who was involved and how many, we don't have the confirmation of that yet," he added.

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

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

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.

WAR.WIRE