There is “no viable alternative” to the UK’s quarantine policy for international arrivals, a Cabinet minister has said.

Culture Secretary Oliver Dowden said testing passengers at airports is not a “silver bullet” allowing restrictions to be eased.

Labour leader Sir Keir Starmer said arrivals from high-risk countries should be tested twice for coronavirus over a number of days to potentially reduce their quarantine period, while the boss of Heathrow Airport declared the UK “needs a passenger testing regime and fast”.

The UK reimposed the self-isolation requirement for people arriving from Spain on Sunday, making the announcement just five hours before the change in policy came into force.

Mr Dowden told BBC Radio 4’s Today programme: “We are not at the point where there is a viable alternative to the 14-day quarantine.

“There is a real risk here – the virus is spreading around the world, it’s rising rapidly around the world.

“We need to ensure that the measures we’ve taken in the UK – which have been very difficult – to keep this virus under control, do not go to waste because we allow cases to come in from elsewhere.”

Appearing on BBC Breakfast, he said coronavirus can “incubate over a period of time”, adding: “There’s not a silver bullet of just testing immediately at the border.”

During a visit to Falmouth, Sir Keir told reporters “we do support measures being taken to quarantine” but pointed to evidence suggesting the duration could be reduced with multiple tests.

He said: “There’s some evidence it could be shortened to 10 or nine days but that depends on really effective testing and that is why we have pushed the Government so hard on testing.

“There’s the capacity to test, the Government needs to use that to test on arrival and then after a short interval because if that period of 14 days can be brought down to eight, nine or 10 then obviously there’s a huge benefit in that.”

Heathrow chief executive John Holland-Kaye told the PA news agency that the airport is “ready to go in two weeks” if the Government allows tests to be used to ease restrictions.

He said: “We’ve started to mobilise on that so we can be ready as fast as possible.

Our European competitors are racing ahead with passenger testing. If the UK doesn’t act soon global Britain will be nothing more than a campaign slogan

“The speed really depends on the Government and them putting the legislation in place to allow people to come out of quarantine early if they have passed two tests, and deciding whether the second test has to be after five days or eight days or some other time.”

Heathrow is working with travel assistance company Collinson and ground-handling firm Swissport to develop an airport testing regime.

Passengers would be charged around £140 per test.

Public Health England and the Department of Health and Social Care have met with Collinson to discuss its proposal.

Heathrow made a pre-tax loss of £1.1 billion in the first six months of 2020, down from a £7 million profit in the same period a year ago.

Around 70% of its pre-pandemic demand was on routes not included on the Department for Transport’s quarantine exemption list.

Preliminary modelling from the London School of Hygiene and Tropical Medicine suggested 94% of coronavirus cases would be detected if the quarantine period was cut to eight days and passengers tested negative on the seventh.

Shorter quarantine periods “can prevent a substantial amount of transmission”, the research indicated.

Some 88% of cases would be identified if travellers self-isolate for six days and test negative on the fifth day, according to the study.