Portugal is re-imposing border controls as a security measure during the Euro 2004 football championships.
The government said the controls - which will be brought in at the end of May until after the 4 July final - would help weed out trouble-makers.
Portugal is a signatory to the Schengen agreement, which abolished border checks between 15 EU countries.
More than a million tickets have been sold for Euro 2004, and Portugal is expecting 1.5 million extra visitors.
Interior Minister Antonio Figueiredo Lopes put forward the idea in March - the same month that train bombings in neighbouring Spain killed nearly 200 people.
The cabinet approved the plan on Wednesday.
"The reintroduction of border controls will focus particularly on people who have been identified as having a history of causing disturbances," he said.
The border checks will cover the Rock in Rio music festival, from 28 May, as well as the football championships.
"The success of Rock in Rio and Euro 2004 will depend on the planning and execution of a vast series of measures to safeguard the security of the participants and spectators," said the minutes of the cabinet meeting.
"Among these measures should be efficient and speedy control of travel documents at all frontiers".
Under the Schengen agreement, travellers are not required to show passports.
However, there is a clause in the treaty that allows states to temporarily re-impose border controls under special circumstances.