Portugal plans to open dedicated corridors in its airports so British tourists continue to get fast-track access after Brexit whether the UK leaves with or without a deal, the prime minister, António Costa, has said.

“Millions of Britons visit Portugal as tourists every year – we have to ensure the flow is not interrupted,” Costa said on Thursday. Faro airport in the Algarve and Funchal on the island of Madeira will operate special lanes for UK visitors similar to those for EU nationals, he said.

The prime minister was announcing a package of contingency measures to help the country cope with the consequences of a no-deal Brexit, seen as more likely after MPs decisively rejected Theresa May’s deal this week.

He said €50m (£43m) of credit would also be made available to about 2,800 export-focused companies likely to suffer most should Britain crash out of the EU on 29 March, and 60 extra customs officers were to be hired for post-Brexit border checks.

The estimated 400,000 Portuguese citizens living in Britain will also be offered improved consular assistance to ease any residence, work or labour problems arising from no deal, he said.

Even without a Brexit deal, the estimated 45,000-50,000 British citizens living in Portugal – only 23,000 of whom are officially registered – will be able to retain their residence and other rights, including access to state healthcare and recognition of UK academic qualifications, Costa added.

The economy minister, Pedro Siza Vieira, said Portugal was ready to do this unilaterally. “At this moment we do not even know what the UK wants,” he told Reuters. “What every EU member state is doing is adopting measures that allow them to react to a unilateral circumstance.”

A record 13 million tourists visited Portugal last year, with Britons the largest single group, but the number of UK visitors fell by almost 10% in the first 10 months of last year as the pound has fallen against the euro amid Brexit concerns.

Portugal aims to launch a major promotional campaign targeting Britain in an effort to offset the decline, Siza Vieira said.