European Union (EU) member states have agreed to temporarily suspend travel from southern Africa after the detection of the new Covid variant.
This evening, the WHO classified the new Covid strain as a "variant of concern".
A committee of health experts from the bloc's 27 states agreed upon the need to activate the "emergency break" and impose temporary restrictions on all travel into the EU from southern Africa.
The news was confirmed on Twitter by the Slovenian Presidency of the Council of the European Union.
Meanwhile, the United States said it will restrict entry to travellers from eight southern African countries over concerns about the new variant, President Joe Biden said today.
The policy does not ban flights or apply to US citizens and permanent residents, a White House official said.
The restrictions will be effective from Monday and apply to South Africa, Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique and Malawi.
Canada banned arrivals from seven African countries - Botswana, Eswatini, Lesotho, Mozambique, Namibia, South Africa and Zimbabwe - over concerns about the spread of the new Covid strain.
Earlier, the European Commission recommended that EU countries suspend travel from southern Africa in response to the new variant.
EC President Ursula von der Leyen said the move would help "limit the spread" of the variant, recommending all air travel to affected countries be suspended until more is known about the new strain.
A committee of health experts from all 27 EU states "agreed on the need to activate the emergency break and impose temporary restriction on all travel into EU from southern Africa", the Slovenian presidency of the EU said on Twitter.
Restrictions will apply to Botswana, Eswatini, Lesotho, Mozambique, Namibia, South Africa and Zimbabwe, European Commission spokesperson Eric Mamer said on Twitter.
Taoiseach Micheál Martin spoke to EU chief Ursula von der Leyen this morning to discuss the Europe-wide response to the new Covid variant.
The WHO's Special Envoy on Covid-19 said it is appropriate to be concerned about the new variant.
"My own view is that really it is appropriate to be concerned about this," Dr David Nabarro told the BBC.
"I'll tell you why: The virus looks like it will have greater capacity to evade the defences that we've all built up as a result of the vaccinations we've received since the beginning of this year."
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In Britain, flights from South Africa, Namibia, Lesotho, Botswana, Eswatini and Zimbabwe were suspended from midday today and all six countries have been added to the UK red list.
Passengers - including UK and Irish residents - arriving into Britain from 4am Sunday will be required to book and pay for a government-approved hotel and quarantine for 10 days. They must also take tests on day two and day eight.
British Health Secretary Sajid Javid updated MPs on the variant and said it "is highly likely that it has now spread to other countries".
He added: "We are concerned that this new variant may pose substantial risk to public health. The variant has an unusual large number of mutations.
"Yesterday the UK Health Security Agency classified B.1.1.529 as a new variant under investigation and the very technical group has designated it as a variant under investigation with very high priority."
Mr Javid said early indications show the current vaccines "may be less effective against it".
South Africa says travel bans 'draconian, unjustified'
South Africa's health ministry has attacked Europe's rush to impose travel bans to slow the spread of a new Covid variant as "draconian," unscientific and contrary to WHO advice.
"We believe that some of the reactions have been unjustified," Health Minister Joe Phaahla told a news conference, accusing some leaders whom he did not name of seeking a "scapegoat."
However, the UN's World Health Organization (WHO) on Friday urged against travel curbs at this stage.
The agency cautioned that it could take several weeks to find out whether the newly-discovered mutations made the virus more virulent or transmissible.
Mr Phaala said that bans were "a wrong approach - it's misdirected and goes against the norms and advice by the WHO.
"We feel some of the leadership of countries are finding scapegoats to deal with what is a worldwide problem," he added.
Additional reporting PA