Britain is working to reduce the 14-day quarantine period for arrivals from countries including Spain and France, offering the chance of some respite to a travel industry reeling from the impact of COVID-19.
Health Secretary Matt Hancock said a simple test when travelers land at an airport would not be effective, but the government was looking at ideas such as testing eight days after arrival.
Airline and tour companies have pleaded for a change to the 14-day quarantine rules.
"We are working to find a way that would allow for the quarantine to be reduced, but done in a way that also keeps people safe," Hancock said on LBC radio on Monday.
But he said one test at the airport was not the answer.
"The reason it doesn't work is because this virus can incubate for a period inside your body without a test being able to pick it up," he said.
A test eight days after arrival was one option being considered, he said.
"It is one of the things we'd like to bring in as soon as it's practical to do it," he said.
"It is something that we are working on, but it isn't something that is as straightforward as simply testing people when they get off a plane because of the number of people for whom that wouldn't catch."
(Reporting by Paul Sandle and Elizabeth Piper)
