The French organisers insist that everything possible is being done to ensure that players and spectators are safe at Euro2016 but tournament director Martin Kallen has confirmed that contingency plans have been made to move games and play them behind closed doors if necessary to ensure that the competition is completed on schedule.

"Security is the most important thing for the organisers and for the French state," said France's secretary of state for sport, Thierry Braillard, at a press conference in Paris on Wednesday to mark to start of the final 100-day countdown to the opening match. "There is no higher priority for us whether it is in the stadiums or the fanzones or the cities where the teams are.

“It’s an obligation for us and the French government has done everything to achieve this objective. I don’t know the exact numbers of policemen but (for games) there will be two cordons around the stadium to control access and the video inside it has been improved to make sure that any problem can be spotted. We can’t do more.”

French Football Federation president Jacques Lambert says that security "will weigh like a sword of Damocles over the tournament until midnight on July 10th".

He says that there will be an average of 890 security personnel on duty at every game, a 30 per cent increase on normal levels for the stadiums concerned and he believes that people have been reassured by the precautions being taken with “very few cancellations” by ticket buyers despite the November 13th attacks in which 130 people were killed.

Three suicide bombers targeted the friendly game that night between France and Germany at the Stade de France, and there remains a fear that games at the tournament could be similarly attacked. Casualties would, of course, be the worst case scenario, but it is possible that the tournament might simply be disrupted with the organisers or authorities stepping up precautions to the point whereby a game might have to played elsewhere at very short notice; something Kallen maintains is always part of Uefa’s planning.

“You always have a Plan B, not only for security; you can have a storm that doesn’t allow you to play a match. The tournament is 51 matches in four weeks and you have to play the matches. If a match can’t be played for whatever reason, it needs to be played ASAP; you can’t wait two or three days because then the match schedule will not be working anymore.

“So we need in principle to play the next day and the question then is ‘can you play in the stadium?’ If not, then you might have to play that match in another stadium. Then it depends where that is and how it is prepared. Then you have to consider how you might do the ticketing because the spectators who have tickets for the match in question wouldn’t have enough time to organise travel and a hotel room. And it could be that the match will be behind closed doors because you need to play the match and you are not able to organise everything beforehand.

“We have been working on the security side of things for six years now and we have been working very well with the government, which plays a big part in the security and also the private security. We are pleased with the preparations that have made up to today and we have no major issues.

“If you look at the streets today in Paris, when you walk through the streets, you don’t see a big difference from previous years. France has the situation well under control. They have enough security people in the right places and I think it will be like today; sometimes you will see policemen or members of the military but life goes on as normal.”

Like all of the other participating associations, the FAI has a delegation in Paris attending workshops aspects of the tournament’s organisation at the moment and it says that it is “very happy” with the level of security planning.

More than 30,000 Irish supporters are expected to travel to France for at least one game. Many of those intending to travel are still looking to get tickets and Uefa’s website resale portal will, it has been confirmed, will open next week, on Wednesday, March 9th.