Government confirmation on the first countries to be connected via ‘air bridges' to avoid UK quarantine rules could come as early as today.
The change of policy had been expected on 29 June to coincide with the three-week review of imposition of the 14-day quarantine.
A major travel industry backlash has forced a government rethink over the two-week isolation rule with a series of travel corridors to be established to countries viewed as low risk.
A first phase to be available for travel from 4 July is expected to include popular holiday destinations such as France, Spain, Italy and Greece alongside Gibraltar and Bermuda.
The likes of Germany, Belgium, Netherlands, Austria, Norway, Finland and low-risk island nations are also under consideration.
However, doubts have been cast over the inclusion of Portugal due to an outbreak of Covid-19 around Lisbon, and Sweden due to its higher rate.
There have also been reports of a fresh coronavirus outbreak in the Costa Del Sol after more than 80 people tested positive.
The details of travel corridors could come from Downing Street on Friday afternoon, industry sources suggested.
Paul Charles, spokesman for the Quash Quarantine industry lobby group, said an air bridge to Spain but not Portugal, or any neighbouring EU countries, would be unenforceable and lead to "tourism subterfuge."
"You are not going to be able to stop British people flying to Madrid, driving a car to Portugal, then going back via Madrid," said Charles, chief executive of PC Consultancy.
"That's why it needs a pan-European travel corridor. There are many states in Europe but it is in effect one country because of freedom of movement under Schengen."
Pressure is mounting on ministers after Ireland announced that it will open air bridges to bypass its quarantine from 9 July.