The European Union (EU) aims to halt air travel from the southern African region amid rising concern about a new Covid-19 variant detected in South Africa, EU Commission chief Ursula von der Leyen said on Friday.

"The Commission will propose, in close coordination with Member States, to activate the emergency brake to stop air travel from the southern African region due to the variant of concern B.1.1.529," she said in a tweet.

The executive Commission will recommend that all 27 member states implement the measure and hopes for the European Council to give the green light as soon as possible, an EU official added.

Britain temporarily banned flights from South Africa, Namibia, Botswana, Zimbabwe, Lesotho and Eswatini from Friday, and asked returning British travellers from those destinations to quarantine.

The variant has a "very unusual constellation" of mutations, which are concerning because they could help it evade the body's immune response and make it more transmissible, South African scientists say.

Scientists are still assessing the new virus variant, first identified this week. Its discovery on Friday pummelled financial markets in Asia, where stocks suffered their sharpest drop in three months and oil plunged more than 3%.

Decisions of the European Council, which represents member states, do not have to be taken by ministers but can also be signed off by the country's ambassadors in Brussels.