Police are keeping a lookout at Bristol International Airport for football hooligans going abroad for Euro 2004.
Bristol has seen its share of football-related trouble
Uniformed and undercover officers will be on patrol to check the passports and documents of potential troublemakers.
Operation Half Time, starting on Monday, is part of a national crackdown using new powers.
Officers can detain suspected hooligans for up to six hours while they make inquiries and a ban on travel can be imposed if necessary.
A special watch will be kept for people who are already the subject of a banning order or known to have been involved with violence in the past.
Police say well-intentioned travellers going to Portugal for matches have nothing to worry about.
Under the Football Disorder Act 2000 officers can prevent potential offenders from catching their flights and then apply for a court ban the next day.
Superintendent Adrian Coombs said: "The majority of people travelling through Bristol International Airport and to the tournament are law-abiding and peaceful.
"However, the hooligan element will be looking to travel to Portugal for the wrong reasons and we will do all we can to stop them.
"Hooligans do not comply with the traditional stereotype and will be trying to disguise themselves as genuine travellers.
"We therefore ask people to be patient and co-operate if they are asked for their documents."
Avon and Somerset Constabulary is liaising with other forces to collate intelligence and also working with airlines as part of the operation.
In February, before the England and Portugal friendly match, one man stopped at the airport was given a two-year ban.
This prevents him from attending any football ground in England and Wales on match days and forbids him from leaving the country five days before any England game abroad.