The Iraq crisis and a terrorism scare yesterday sent a sudden shiver through the previously peaceful countdown to the start of the Winter Olympics.

Even if no one was pushing panic buttons before Saturday's opening ceremony of the Games in this mountainous central Japanese city, there was a chill of nervousness in the air.

A White House comment that the Games would not get in the way of a raid on Iraq and a mortar attack on Tokyo airport were grim reminders of how easily the winds of international conflict can blow into a global sporting event like the Olympics.

The events took some shine off the Nagano organisers' formal announcement that a record 72 nations would take part

There was most concern that the United States might destroy a UN-backed "Olympic Truce" by attacking Iraq during the February 7th-22nd Games over Baghdad's refusal to allow UN inspectors access to suspected weapons sites.

White House spokesman Mike McCurry said that President Bill Clinton would not be influenced by "sporting events" during the stand-off with Iraq.

"Not to my knowledge is any decision-making or thinking that the president and his senior foreign policy leaders are undertaking affected by sporting events," McCurry said.

There was an immediate reaction from Games officials, proud of the unanimous United Nations peace resolutions that have been passed for the last three Olympics - the 1994 Winter Games in Lillehammer, the 1996 Summer Games in Atlanta and now Nagano.

They believe the truces live up to the ideals of the ancient Greek Olympics when warring city states agreed to recognise the sanctity of Olympia.

"We would be sad (if war broke out between the US and Iraq) because any kind of conflict makes all of us sad," International Olympic Committee director general Francois Carrard said.

"But, what can we do? We are not politicians. We are not making decisions."

Japanese security chiefs had no hesitation in acting swiftly after a Monday night mortar attack on Tokyo's Narita Airport, gateway for thousands of foreign athletes and spectators now pouring into the country for the Games.

Although no one claimed responsibility and, despite past attacks by leftist radicals linked to expansion of airport runway capacity, no chances were taken.

Fearful it could be an offensive by radicals to prove they were still a potent force, police immediately stepped up security at the airport and five hours drive away at Nagano and the five outlying villages where competition takes place.

"This incident at Narita has made us very worried and nervous," Nagano police spokesman Masayuki Muramatsu said.

Carrard said the IOC was being kept informed of the situation. `We have been told, of course, that security measures have been upgrade and reinforced," Carrard said.

Muramatsu said extra burdens placed on security staff because of the mortar attack could indirectly affect the Games.