KUWAIT (AP) _ Kuwait has completed a chain of air, sea and ground defenses in anticipation of a spillover from the 41/2 -year-old Iran-Iraq war, Defense Minister Sheik Salem al-Sabah was quoted Saturday as saying.

Kuwait's Bubiyan Island was reported turned into a military zone.

''The war might creep to Kuwait territory any moment,'' Salem was quoted as warning in an interview with the radical newspaper Al-Watan. ''And we have taken every precaution necessary to face this eventuality.''

He said, according to the newspaper, that the tiny, oil-rich country has consolidated its sea, ground and air defenses and turned Bubiyan into a ''purely military island, equipped with strong anti-aircraft defenses.''

''No vistors are allowed to approach Bubiyan any longer,'' he was quoted as saying.

Kuwait and its allies in the six-nation Gulf Cooperation Council - Saudi Arabia, the United Arab Emirates, Bahrain, Qatar and Oman - have been ''watching the recent fighting, which appears to be settling to a pattern of attrition,'' Al-Watan quoted him as remarking.

He was alluding to the week-long Iranian offensive into the Iraqi region of Huwaizah marshlands, begun March 11, when the invaders tried without success to drive a wedge into a southern Iraqi highway and isolate the Basra region.

Bubiyan, a small island 87 miles northeast of Kuwait City, has been fortified with infantry troops and batteries of anti-aircraft guns and missiles, according to Arab diplomatic sources in Kuwait, who spoke on condition of anonymity.

Two years ago, Iraq asked Kuwait to lease Bubiyan to the Iraqi navy, but the government of Sheik Jaber al-Ahmed declined.

The Kuwaitis have been trying to stay neutral, although their newspapers and broadcast media have been outspoken supporters of Iraq.

Salem was quoted as saying that an early warning system has been installed for the defense of Kuwait against intruding aircraft.

Responding to a question, Salem said, according to the paper, that the Gulf Cooperation Council members were in the process of setting up a joint defense forces called the ''Peninsula Shield.''

He said Kuwait was to contribute two battalions and Saudi Arabia, a brigade. The force would be commanded by a Saudi general.

''The GCC countries have been swapping information and expertise, with a view to making the region immune against the eventuality of aggression,'' he was quoted as saying. ''We have been watching air activities in gulf skies, and we have developed a system whereby hostile aircraft can be intercepted and driven away.''

Salem warned Iran that Kuwait would confront any invader, Al-Watan reported.

''If they (the Iranians) were brave, then let them come to my land and I will be ready for a confrontation,'' he was quoted as saying.

Al-Watan quoted Salem as saying, without giving details, that a ''reserve army of conscripted men'' will be assembled in the years to come to serve as a ''second line'' for the regular army.

Kuwait's armed forces of 12,500 men are equipped with U.S., British, French and Soviet weapons, including French Mirage F-1 and U.S. Skyhawk warplanes.

Its air defense systems include U.S.-made Hawk missile batteries and Gazelle helicopter gunships, supplied by France.

British-made Chieftain tanks and other types of French-made military hardware make up the backbone of the ground forces.