Up to 500,000 British football fans, around half of whom do not have tickets, are expected to travel to France for Euro 2016, police have said.
Potential flashpoints include the England-Wales game in Lens, and England’s fixture against Russia in Marseille, which saw ugly clashes between home supporters and riot police in the 1998 World Cup.
British police are hoping to act as “cultural interpreters” to prevent heavy-handed tactics against drunk and rowdy fans who may not cause serious trouble.
Police delegations representing England, Wales and Northern Ireland are set to travel to the tournament, which has seen massive demand for tickets from the home nations.
French authorities have already told English and Welsh fans without tickets not to travel to Lens, and there will be an alcohol ban in the city centre for 24 hours on match day.
England and Wales were each allocated 9,000 tickets for the game, but there were more than 20,000 applications.
In total, around 250,000 UK supporters have tickets, but it is expected that double that number of fans will travel to France.
Currently 1,841 England fans and 86 Wales supporters are under banning orders that apply from May 31 to July 11 and mean they must hand in their passports to police.
An operation covering 29 UK ports with officers from 19 police forces will launch on June 6, with specially trained “spotters” to detect hooligans trying to sneak out of the country.
Assistant Chief Constable Mark Roberts, the national lead for football policing, warned that the banning orders are no guarantee against trouble.
He said: “Some of the people who have drunk to excess and behaved in an anti-social manner are not known to the police.
“They are not people who we have on the periphery or the radar as saying these people will cause trouble at football. They don’t have previous convictions sometimes in any matter, let alone football.
“We’ve got to be aware that even if you have a banning order operation that doesn’t entirely guarantee that you won’t have problems.
“And if we have up to 500,000 people travelling, it being summer they will no doubt drink, they will be in large groups, and we need to be aware that there may be potential trouble.”