France is expecting around 10 million visitors during Euro 2016, which kicks off tonight with France facing Romania.
Strike action if threatening to overshadow the football tournament, with Air France grounding flights on Sunday, trains cancelled and oil refineries hit by blockades in protest against labour reforms.
Fans are also warned to remain alert to the threat of terrorism.
The are 24 teams in the tournament; 16 of them will progress to the second round.
Around 100,000 Irish fans will travel to the games, but with security expected to be tight they have been warned to expect major delays.
Armed guards are accompanying the Irish football team ahead of tonight's European Championship kick off in France.
All fans have been warned to turn up three hours early for matches.
Ireland's first match is on Monday against Sweden.
Meanwhile, two English football fans have been arrested after French police used tear gas to disperse an apparent clash with locals in Marseille ahead of the first games of the tournament.
One England supporter suffered a head injury in the brawl after being hit across the face with a wooden chair.
Gendarmes clad in riot gear and accompanied by dogs were deployed on the streets of the southern city after trouble flared outside a pub shortly before midnight on Thursday.
Police said one of the fans was arrested for assaulting a barman and the other for violent disorder.
According to reports local "ultras" descended on the pub, but this has not been confirmed.
Supporters have travelled to Marseille ahead of England's game with Russia on Saturday.
Kevin Miles, chief executive of the Football Supporters' Federation which runs the fans embassy in Marseille, said he believed the locals turned up with the intention of provoking the English fans.
"There's not huge numbers of England fans in town yet, probably the biggest congregation anywhere was outside this pub," he said.
"People were drinking and having a bit of a sing-song all day, the French police were very relaxed, letting them get on with it.
"It was all fine until, our understanding is, a group of around 30 to 40 locals turned up, I think with the intention of provoking the England fans to see if they could get a rise out of them.
"In those circumstances it's the police's job to prevent a confrontation and they used French methods to do so, which we're not particularly used to.
"They used tear gas, which is a little bit indiscriminate for my liking, but it did the job and the problems were over. There were a couple of arrests of English fans as they responded to that provocation."
He said: "The police have confirmed that version of events. I understand one England fan has been treated in hospital for a head injury which apparently isn't serious, and there have been two English arrests."