Japan will tighten restrictions on travelers from South Africa and five nearby countries after the discovery of a new coronavirus variant there, the government's top spokesman said Friday.

Travelers who have recently been to Botswana, Eswatini, Lesotho, Namibia, South Africa or Zimbabwe will be required to spend 10 days in a government-designated facility upon their arrival, Chief Cabinet Secretary Hirokazu Matsuno told a press conference.

The move, which takes effect Saturday, comes amid mounting concerns over the spread of a coronavirus variant known as B.1.1.529, which infectious disease experts warn could be more contagious than previous strains or render existing vaccines less effective.

Chief Cabinet Secretary Hirokazu Matsuno holds a press conference at the prime minister's office in Tokyo on Nov. 26, 2021. (Kyodo)

Britain has temporarily suspended all flights from the six countries in southern Africa, and the World Health Organization has called a special meeting to discuss the variant.

After leaving the government-designated facility, travelers from South Africa and the nearby countries will need to spend a further four days in quarantine at home to ensure they are not infected. Previously, they would have been allowed to spend all 14 days at home.