A letter signed by 13 MPs, including six former ministers, proposes testing at five days, which the MPs say could catch at least 88% of cases. 

The Telegraph says the government’s current thinking favours testing after seven days, releasing those who prove negative half way through the 14-day quarantine. However, the newspaper said it understands tests at eight and 10 days are also under consideration.

The MPs’ letter cites a model by the London School of Hygiene and Tropical Medicine, which showed a test on the fifth day of quarantine would catch 88% of infected travellers, with tests on the seventh day showing only marginal improvements in detection.

The letter said the day five tests should be a precursor to pre-departure testing, which would mean arrivals could be released from quarantine two days after they return home from the UK.

In the letter, former Brexit minister David Davis said: "Five days works in places like Germany, is aligned with the science and would be a start.

“Any longer and the danger is that testing simply won’t have the impact on demand that the UK’s aviation industry needs it to have."