The comments come after the US announced that one plane had come under fire in the north, and three missiles had then been targeted on an Iraqi anti-aircraft position.

President Clinton: "We will continue to enforce no-fly zones"

US officials said there would be a decisive response to any further Iraqi threats.

President Bill Clinton said the no-fly zones were an important part of the US "containment strategy" against the Iraqi Government.

He said the two zones, one in the north and one in the south stretching from the Baghdad suburbs to the border with Kuwait, were there to prevent aggression by Baghdad.

The BBC's Tom Carver: "Saddam Hussein still controls the initiative"

But in an escalating war of words Iraq said it did not recognise the exclusion zones and would confront any western military plane entering its air space.

Baghdad's UN envoy, Nizar Hamdoon, said: "Iraq has always said that there is no way that it could recognise the no-fly zones. Why should there be such a breach of Iraq's sovereignty? Why should Iraq stand idle?"

Conflicting accounts

Iraq says four of its soldiers were killed and an "enemy" plane was almost certainly shot down during Monday's exchange of fire. The Americans say all planes returned safely to base in Turkey.

An Iraqi communiqué, reported by the official INA news agency said: "Enemy planes flying out of Turkey violated Iraqi airspace at 13:37 local time (1037 GMT Monday) and approached anti-aircraft positions before firing missiles on one of the positions."

The Pentagon and the UK's Ministry of Defence confirmed the missiles were fired at an Iraqi anti-aircraft installation just north of Mosul, but said it was in retaliation for an attack from the anti-aircraft base.

Mr Clinton defended the action as a legitimate act of self defence.

Baghdad Correspondent Caroline Wyatt: "War of words"

Pentagon spokesman Colonel Richard Bridges said US F16 warplanes fired on an Iraqi target in response to "an act of aggression" while pilots were enforcing the northern no-fly zone.

A spokesman for the UK Ministry of Defence said: "There are reports of US aircraft coming under attack from surface-to-air missiles in the north of Iraq.

"Under the rules of engagement, the (planes) are allowed to defend themselves."

He added that no UK planes were involved in the incident.

Our correspondent in Baghdad, Caroline Wyatt, says Iraq is keen to portray itself as the victim of Western aggression, and thereby win diplomatic support.