Portugal has started rationing petrol as a precaution after 2,000 lorry drivers began an open-ended strike over pay, a move that comes at the height of the crucial summer tourist season and during the summer harvest.
The government set a limit at gas stations of 25 litres (6.6 gallons) for light vehicles and 100 litres (26.4 gallons) for lorries until further notice as most tanker drivers walked off the job.
Some hauliers in other sectors of the economy also joined the walkout.
Anticipating petrol and fresh food shortages, the centre-left Socialist government, which faces a general election in October, is forcing hauliers to provide a minimum volume of supplies.
Authorities hope to minimise disruptions by demanding that drivers maintain petrol supplies to emergency services and airports, provide 75% of normal petrol deliveries for public transport systems and 50% to petrol stations.
All perishable goods and at least half of the normal food supplies must also be delivered to stores.