The country declared an “energy crisis” on Tuesday (16 April), the Financial Times reports, requiring drivers maintain supplies to ensure key civil and infrastructure services continue.

Prime minister Antonio Costa said on Wednesday (17 April) the government was seeking to resolve the dispute between firms and Portugal national union of dangerous goods drivers.

Dwindling supplies have already affected Portugal’s main airports, with fuel running low at Lisbon, Porto and Faro, and threatens to disrupt travel to the country over the Easter weekend.

The country’s main airport operator ANA has warned air passengers their journeys could be affected.

“Due to a national strike, aircraft fuel supply is restricted, so there might be changes to your flight,” said ANA in a statement, urging passengers to check the status of their flight with their airline.

Airlines, including easyJet, have been forced to refuel en route to Portuguese airports this week for fear of not being able to refuel when they arrive.