The industry should expect few additions to the list of countries open to travel without quarantine restrictions following the government review due on Monday.

Sources leading the engagement with ministers warn “it would be wishful thinking” to expect many changes “at this stage”.

At the same time, they caution things could go backwards, with an airline source warning: “The government won’t hesitate to pull it all back if we get an outbreak. At any moment, a market could be cut off.”

The Foreign Office confirmed on Thursday that Public Health England was monitoring recent reports of “substantial increases” in cases of Covid-19 in the Spanish regions of Aragon and Catalonia, which include the cities of Zaragoza and Barcelona.

The source ruled out “large-scale changes” on July 27 and said: “There will be tweaks. We don’t foresee swathes of countries being added. Obviously, we would like Portugal brought back. We hope they will add countries as they’re able to.”

A second source agreed: “We don’t have much hope for the review. We’ve not heard of any countries being added.”

The airline source added: “There is no detail on how they will conduct the review. The decisions are made behind closed doors. A lot of countries are trying to get to grips with what is required. We would like more detail.”

Airlines are lobbying for the government to ‘open’ hub airports such as Dubai and Abu Dhabi. The current guidance means travellers spending any time at a hub have to quarantine upon UK arrival.

The source said: “There are hubs where, if transit traffic remains segregated, it could be separated from the situation in the country. We hope that is under consideration.”

Ministers reportedly intend to replace a three-weekly review of “safe” destinations with one in which countries are added or excluded depending on spikes or drops in coronavirus cases.

That will allow a more flexible response to open up countries to travel as their infection rates fall and exclude those hit by a second wave, even though holidaymakers could face a period of quarantine on their return.

The Department for Transport is also considering regional ‘air bridges’ which would allow travel to low-risk regions such as the Algarve, Madeira and the Azores but exclude Lisbon, which accounts for most of Portugal’s new cases.

The country was excluded from the UK’s initial ‘Covid safe travel’ list of destinations which came into force on July 10.

But hopes of Covid-tests on passengers leading to a relaxation appear stalled despite a trial at Heathrow and other airports.

An aviation source said: “Optimism about testing has waned. There are problems making it work [given] the accuracy of picking up passengers with asymptomatic infections. The success is in single digits, which means looking to do a second test. There is not much hope of clarity any time soon.”

The airline source agreed: “We’re stuck to four-week cycles. The government has said, ‘The review period will be the review period’. But we hope if a major market [can be brought back], they would announce it and not wait.”