Travellers arriving in England from several southern African countries will have to quarantine amid warnings over a new coronavirus variant.
UK Health Secretary Sajid Javid said from 12:00 GMT on Friday six countries would be added to the red list, with flights being temporarily banned.
One expert described the variant, known as B.1.1.529, as "the worst one we've seen so far", and there is concern it has the potential to evade immunity.
No cases have been confirmed in the UK.
Only 59 confirmed cases have been identified in South Africa, Hong Kong and Botswana so far.
All flights from South Africa, Namibia, Zimbabwe, Botswana, Lesotho and Eswatini are being suspended.
Mr Javid said that scientists were "deeply concerned" about the new variant but more needed to be learned about it.