Airlines are not always checking if travellers from certain countries have tested negative for coronavirus before they fly back to the Netherlands, according to an investigation by current affairs show Nieuwsuur.

Travellers from Spain and Italy have been required to show negative tests for some time and other popular holiday destinations, such as Italy, were added to the yellow list at the weekend.

However, random checks at Eindhoven Airport showed that 5% of people returning from a holiday did not have a valid negative test certificate.

‘We make a note of the airline and the transport inspectorate will carry out a further investigation,’ regional safety board region spokesman Adrie Hofman told broadcaster NOS.

One of the offending airlines is budget carrier Transavia, Nieuwsuur said. It claims, for example, that passengers on two flights from Spain were not checked at all.

The transport inspectorate confirmed it is investigating a case but will not say which airline or flight it involves. Airlines which are repeatedly found at fault can be fined.

In a reaction, Transavia said all staff abroad have been instructed to check for negative test results.

D66 MP Jan Paternotte said the lack of control was ‘baffling’ because airports are in a position to carry out the checks without any difficulty. Fellow MP Joba van den Berg (CDA) has asked the cabinet for an explanation. ‘If people can’t prove they’re negative they should not be allowed on the flight,’ she said.

The number of checks on arrivals at Dutch airports will not be increased, a health ministry spokesman said.