Travellers arriving from several southern African countries will have to quarantine amid warnings over a new Covid variant, the Health Secretary announced tonight.

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.

He said that scientists were "deeply concerned" about the new variant but more needed to be learned about it.

But he said that what we do know is that there is a significant number of mutations, "perhaps double the number of mutations that we have seen in the Delta variant".

He added: "And that would suggest that it may well be more transmissible and the current vaccines that we have may well be less effective."

He said adding the six countries to the red list was about "being cautious and taking action and trying to protect. as best we can, our borders".

Anyone arriving from the countries after 04:00 on Sunday will have to quarantine in a hotel, with those returning before that being asked to isolate at home.

Those who have returned in the last 10 days are being asked to take a PCR test.