Baghdad last night accused the US of "unjustified aggression" after a US warplane fired a missile at an Iraqi radar site when four RAF Tornado jets appeared to be under threat of attack.
The Tornado crews, on a routine patrol enforcing a no-fly zone south of Basra, alerted a US F16 escorting them after an Iraqi radar locked onto their aircraft and two others, the British Ministry of Defence said. All the planes returned safely to base.
Iraqi officials denied its radar locked onto the aircraft, describing the action as "proof of the aggressiveness of Americans".
They said the US missile fell 18km away from the nearest radar.
In Washington, the US Defence Secretary, Mr William Cohen, described the missile attack as a warning to Baghdad.
"We're hoping that the situation won't escalate. It certainly was a signal that we sent that our forces are going to fly the no-fly zone," he said.
Asked why he believed the Iraqis had locked onto the planes, he said: "There is no way to tell what their motivation may have been and what their reaction will be."
Yesterday's incident came as tension in the Gulf appeared to have eased. Mr Cohen said it would not alter US plans to continue withdrawing forces from the region. The US vice-president, Mr Al Gore, warned against assuming that it was a deliberate provocation.
The incident follows accusations of Iraqi foot-dragging in providing information to UN weapons inspectors.
Mr Richard Butler, the chief UN weapons inspector, last week said that Iraq was still refusing to provide information on missiles, biological weapons and the chemical warfare agent VX, despite Baghdad's claim of a breakthrough on UN arms inspections.
Mr Butler's report to the security council, based on his talks in Baghdad earlier this month, casts doubt on claims that Iraq may soon be free from sanctions - unless the council softens its demand that Baghdad first account for all long-range missiles and nuclear, chemical and biological weapons.
Iraq is apparently gambling that its sympathisers - Russia, France and China - will prevail over the US and Britain and persuade the council to end the sanctions without complete verification that all illegal weapons have been destroyed.
Yesterday's incident is likely to arouse concern among Iraq's friends that Baghdad may undo its recent diplomatic gains.
Russia urged the US to exercise restraint. "It is necessary to localise the incident and prevent its escalation," said a Foreign Ministry spokesman, Mr Vladimir Rakhmanin.
Farouk Choukri reports from Baghdad:
An official Iraqi spokesman said that the F-16 fighter which fired the missile was aimed at drinking water reservoirs in an area where no military units operate.
The spokesman, quoted by the official news agency INA, said the attack aimed at water reservoirs near the Gulf port of Umm Qasr in the Basra region of southern Iraq.
Iraqi anti-aircraft defences were not activated, he said, accusing US and British aircraft of violating Iraqi airspace. The spokesman did not report casualties or damage.
The attack was "unjustified. . . and proof of the aggressive intentions of the United States and its contempt for the security and sovereignty of other peoples," the spokesman said. He charged that the attack could be part of US preparations for "a vast new aggression against Iraq".
US and British aviation patrol the southern no-fly zone, which was set up in 1992 to protect the region's Shi'ite Muslims from Iraqi attack. A similar zone in northern Iraq, to protect the Kurds, was set up in the aftermath of the 1991 Gulf War.
Brent oil, the North Sea benchmark crude, rose sharply yesterday in London following the attack.