Portugal will allow tourist flights from European Union countries with low infection rates and from the United Kingdom, but passengers must show proof of a negative COVID-19 test upon arrival, the Interior Ministry said on Saturday.

The ministry’s announcement came a day after the Portuguese tourism authority gave the green light to UK tourists to enter the country from Monday.

It said in a statement that the ban will be lifted on EU countries with less than 500 cases of COVID-19 infections per 100,000 people.

Tourists from Switzerland, Iceland, Liechtenstein and Norway are also allowed to start flying to Portugal.

Visitors will have to present a negative test taken up to 72 hours before a flight, and airlines will be fined between 500 euros ($607) and 2,000 euros for each passenger who boards without showing proof of a negative test.

Portugal currently only allows essential flights for family reunion, humanitarian, professional, study or health reasons.

Travelers from countries where 500 or more cases per 100,000 people have been registered over a 14-day period can only enter Portugal if they have a valid reason, such as for healthcare or work. Arrivals must then quarantine for a period of 14 days.