Portugal's foreign minister has said anyone in the UK thinking of going to Portugal this summer will be "most welcome" amid coronavirus.
Augusto Santos Silva said he hoped an air bridge between the UK and Portugal could be secured by the end of June.
The UK is set to give more details of its plan to force arrivals into quarantine for 14 days later.
UK Home Secretary Priti Patel will say air bridges to countries with low virus infection rates are possible in future.
This would mean that people arriving from certain places will not have to self-isolate.
However, that will only apply to countries with low Covid-19 infection rates, she is expected to tell MPs. She will also say that the planned quarantine for arrivals is necessary "to prevent a second wave of the virus".
Meanwhile, Heathrow boss John Holland-Kaye has told BBC Breakfast that travellers will have to fill out details of where they will be staying to quarantine, when they book their flight.
He said there will then be "spot checks" within the immigration area, where the Border Force officers will check if people have filled out their form.
"All of the form-filling will take place before you get on a plane, and will be done online. The government will be able to check information before people get onto a plane," he said.
Some countries have already started to ease travel restrictions. The German foreign minister Heiko Maas said the country would lift a travel ban for EU countries, as well as the UK and a handful of others - as long as they do not have large-scale lockdowns in place.
However, Germany will advise against travel to Britain for as long as the UK government demands a 14-day quarantine for new arrivals.
Portugal's Mr Santos Silva told the BBC that an agreement between the UK and Portugal could be in place by the end of June, meaning that holidaymakers returning to the UK from Portugal would escape the quarantine rules.
He said any travel quarantine "was an enemy of tourism", but that he respected the UK government's decision to enforce one on almost all arrivals to the UK from next Monday.
Mr Santos Silva said "rules" would ensure that people would be able to holiday safely.
The minister suggested that nightlife in Portuguese resorts this summer would be very limited and people would not be allowed to congregate in groups at night.
He said hotels and apartments which comply with standards set by the tourism board would be labelled as "clean and safe".
Portugal's foreign minister confirmed talks on the matter were continuing with the UK.
But he insisted that Portugal would not impose any type of quarantine for people arriving in his country.
Instead, he said Portugal would rely on temperature checks at airports and that Portugal was, in coordination with other EU countries, considering carrying out "random testing" on passengers.
Mr Santos Silva said tourists would be warned how full beaches are, so that they could avoid crowded spots.
UK aviation bosses hope that a large number of air bridge agreements will be in place by 29 June, when the travel quarantine is set to be reviewed.
More tourists from the UK head to the Algarve each summer than from any other country.
But Spain, another country whose tourism sector relies heavily on British holidaymakers, is taking a different approach.
The Spanish government has said it will only allow UK tourists in this summer if the infection rate in the UK falls more significantly.
The UK travel quarantine will apply to people arriving from any country, apart from the Republic of Ireland, and will also apply to UK nationals.
People will be required to self-isolate in a private residence for two weeks.
The government says people "could be contacted regularly during this period to ensure compliance".
People who break the rules could be fined £1,000.
UK travel companies say the travel quarantine already means people are not booking holidays. They warn that more businesses in the sector now face financial ruin.
The measure will be reviewed every three weeks.
When deciding whether to keep the quarantine in place, the government will consider several factors. They include:
- the rate of infection internationally
- prevention measures in other countries
- the extent to which other countries with more relaxed border arrangements have seen imported cases
- the effectiveness of testing methods at minimising the risk of new cases of the virus entering the country.
A growing list of Conservative MPs have spoken out against the blanket travel quarantine.
However, a YouGov poll of 1,565 adults in Great Britain suggests that there is public support.
63% of those surveyed thought people should be quarantined as per the government's plan.
About one quarter thought that the quarantine should only apply to people arriving from countries with a "high number of coronavirus cases". Only 4% thought that there should be no quarantine at all.
Labour has questioned why a travel quarantine was not introduced some weeks ago.
New figures show that between the beginning of January and the end of April, 14,225 flights arrived into UK airports.