LONDON: Britain will confirm in early May whether it will allow international travel to resume from May 17 and which countries will fall into the red, amber or green categories in a traffic light system based on COVID-19 risks.

Airlines, desperate for a bumper summer after a year of restrictions, criticised proposals from the government's Global Travel Taskforce, which include COVID tests, saying the 100 pound cost of PCR testing for those arriving from low-risk green countries would put off many travellers.

Giving new details of how it hopes to allow people to travel this summer, the taskforce also said work was going on to develop a certification system, sometimes called "vaccine passports", for inbound and outbound travel.

Britain is gradually emerging from a strict winter lockdown prompted by a surge in COVID-19 infections and deaths. As things stand, international travel is banned except under specific circumstances defined by the government.

But the government's proposals for restarting travel fell short of airline industry hopes.

"This does not represent a reopening of travel as promised by ministers," said Airlines UK, an industry body which represents British Airways, easyJet, Ryanair, Virgin Atlantic and others.

EasyJet, Britain's biggest airline by passenger numbers, said the PCR test requirement for low-risk countries was a blow to travellers and called on the government to re-assess its plan.

"This risks reversing the clock and making flying only for the wealthy," said easyJet chief executive Johan Lundgren.

Case numbers in Britain have dropped dramatically since the January peak but a government priority is to avoid undermining the success of its vaccination programme by importing vaccine-resistant variants from overseas.

"The framework announced today will help allow us to reopen travel safely and sustainably, ensure we protect our hard-won achievements on the vaccine rollout and offer peace of mind to both passengers and industry as we begin to take trips abroad once again," said Transport Secretary Grant Shapps.

The government said it was working with the travel industry and with private COVID-19 test providers to cut the cost of travel.

"This could include cheaper tests being used when holidaymakers return home, as well as whether the government would be able to provide pre-departure tests," the travel taskforce said.

Under the traffic light system, restrictions such as hotel quarantine, home quarantine and compulsory COVID tests will apply differently depending on which category of country a passenger arrives from.

Factors in assessing categories will include the percentage of the population that has been vaccinated, the rate of infection, the prevalence of variants of concern and the country's access to reliable genomic sequencing.

There will be a "green watchlist" identifying countries most at risk of moving from green to amber, although the government said it would not hesitate to change a country's category should data show risk had increased.

The taskforce indicated that a digital travel certification system would be part of the plan but gave few details beyond saying that Britain wanted to play a leading role in developing standards in this area.