The F-16 was patrolling the no-fly zone when it was illuminated by the radar from a missile battery, indicating that it was at risk of being fired on, National Security Council spokesman P J Crowley said. The pilot fired a harm missile targeting the battery in `legitimate defence,'' he said.

``We have no assessment at this point'' of the damage caused by the missile, he added. A combined task force statement from Incirlik air base in Turkey, from where US F-16s patrol the northern no-fly zone, said the incident took place ``on january seven at approximately 11:20 Iraqi time''.

``Saddam Hussein's regime once again violated cease-fire accords by locking their surface-to-air missile radar on to coalition forces monitoring the northern no-fly zone,'' the statement said.

``A US F-16 acted in self-defence and fired ahigh-speed anti-radiation missile (HARM) to suppress the offensive site.'' The latest incident followed clashes on Tuesday reported by the Pentagon between US warplanes and Iraqi fighters in the no-fly zone in southern Iraq.