Lieutenant Nick Ferrier of the Irish Guards said around four or five shots had been fired at around 1100 GMT although it was not clear if the British soldiers were the target.

"We don't know if it's just an act of defiance or aimed at us," said Ferrier. "It's impossible to pinpoint where it's from."

Some troops could be seen ducking on street corners and behind electricity pylons, firing off cover shots for fellow Guardsmen who ran down side streets in the direction of the gunfire.

After failing to find the source of the shooting, the troops resumed their patrol.

British forces took control of Basra nearly two weeks ago and the sound of gunfire can still occasionally be heard in the city, but rarely during daylight hours.

SPACE.WIRE