Passengers flying from Heathrow to Hong Kong and Italy on Tuesday will be the first to have the option of paying for a rapid Covid test before checking in.
The test will cost £80 and the result is guaranteed within an hour.
The aim is to help people travelling to destinations where proof of a negative result is required on arrival.
A growing number of countries have classified the UK as being “at-risk”, meaning travellers from the UK face more restrictions.
The authorities in Hong Kong now require people to show they have a negative test result, taken within 72 hours of a flight from London.
The rapid saliva swab, which is now available at Heathrow Terminals 2 and 5, is known as a Lamp (Loop-mediated Isothermal Amplification) test. Covid
British Airways, Virgin Atlantic and Cathay Pacific will now offer it to customers.