* France first country to raise security concerns
* Site of Pyeongchang just 80km from N.Korea border
* Tensions high after nuclear and missile tests, sanctions
* Other countries monitoring situation, IOC says no Plan B (Add comments from games organiser, Japanese Olympic committee and background)
PARIS/SEOUL, Sept 22 (Reuters) - France's Winter Olympics team will not travel to the 2018 Games in South Korea if its security cannot be guaranteed, France's sports minister said on Thursday, the first major doubts by a participating nation about growing North Korean tensions.
The games organiser said on Friday that it is closely monitoring the current geopolitical situation with the South Korean government, adding that safety is the top priority.
Tensions in the region have escalated since North Korea conducted its sixth and largest nuclear test on Sept. 3, prompting global condemnation.
North Korea's leader Kim Jong Un said on Friday the North will consider the "highest level of hard-line countermeasure in history" against the United States in response to U.S. President Donald Trump's threat to destroy the North.
France's Sports Minister Laura Flessel told RTL radio that if the crisis deepened and "our security cannot be assured, the French Olympics team will stay at home."
But she added: "We're not there yet."
Participants in the Games - the first Winter Olympics hosted by an Asian nation outside Japan - had not previously raised safety concerns publicly.
The games are scheduled for Feb 9-25 next year in Pyeongchang, just 80 km (50 miles) from the demilitarised zone between North and South Korea, the world's most heavily armed border. The two countries remain technically at war after their 1950-53 conflict ended with a truce and not a peace treaty.
"Safety and security is one of the most important aspects of Games preparations," Sung Baik-you, a spokesman for the organising committee, said in a statement to Reuters on Friday.
South Korea's President Moon Jae-in said on Wednesday the country is pushing to ensure security at the Pyeongchang Winter Olympics. In a meeting with International Olympic Committee (IOC) President Thomas Bach, Moon said South Korea is well aware of the concerns.
The Japanese Olympic Committee said on Friday it is not considering the cancellation of its plans.
"We will continue to prepare in the same way as with other international competitions that we take part in," a spokeswoman for the committee said.
The United States Olympic Committee (USOC) said it was working with all the relevant authorities to ensure its athletes would be safe.
"Each host city presents a unique challenge from a security perspective, and, as is always the case, we are working with the organisers, the U.S. State Department and the relevant law enforcement agencies to ensure that our athletes, and our entire delegation, are safe," USOC spokesman Patrick Sandusky said.
The Chinese Olympic Committee said it had no immediate comment.
The Canadian Olympic Committee (COC), which has representatives in South Korea, said the safety of its team was always its main priority.
"The safety of our entire Canadian Olympic Team is always our main priority, no matter where the Games are held," the COC said in a statement emailed to Reuters.
"The Government of Canada does not currently have travel advisories in place for South Korea and recommends that Canadians exercise normal security precautions, which is the lowest of four risk levels."
Australia, one of Asia's largest participants at recent Winter Games, is monitoring the situation.
"The safety of our team is of the highest priority but we are comfortable with the priority that the (International Olympic Committee) and the Org Comm are placing on security and safety of the Games and its participants," the Australian Olympic Committee said in a statement emailed to Reuters.
"We are relying on advice from DFAT (Department of Foreign Affairs and Trade) and working with the Korean Ambassador and if their advice changes, we will advise our team accordingly but for the moment there is no suggestion that the Games will not go ahead or their safety is compromised."
The chief of the International Ski Federation, Gian-Franco Kasper, dismissed any fears among athletes, saying the Pyeongchang Olympics would be the "safest in the world".
He conceded, however, that ticket sales among overseas visitors could be affected.
The IOC has said it is not contemplating any 'Plan B' for the Games.
IOC President Thomas Bach said last week that considering any scenario other than holding the Olympics in South Korea could hamper diplomatic efforts. (Reporting by Richard Lough, Elizabeth Pineau and Sarah White; Additional reporting by Frank Pingue in Toronto and Ian Ransom in Melbourne, Australia, Hyunjoo Jin and Christine Kim in SEOUL and Elaine Lies in TOYKO; Editing by Pritha Sarkar, Lincoln Feast and Neil Fullick)