Japan has expanded its travel ban on foreigners entering the country, barring residents of 10 southern African countries from entering.

Japan implemented some of the most stringent measures globally on Monday, shutting its borders to non-Japanese for around a month in response to the development of Omicron. A day later, Japan's first Omicron case - in a Namibian diplomat - was discovered.

Prime Minister Fumio Kishida explained that the policy, which reverses a three-week-old relaxation of travel restrictions, is necessary to "prevent the worst-case situation."

JAL and ANA, two Japanese airlines, also said that they would ban new international flight reservations to Japan until the end of December, while NHK public television reported that the government was aiming to halt all such reservations.

The residents-only border closure will begin at 12 a.m. on Wednesday. It will affect foreign residents from South Africa, Angola, Eswatini, Namibia, Malawi, Zambia, Lesotho, Mozambique, Botswana, and Zimbabwe.

Additionally, 14 nations and locations, including the United Kingdom and Germany, have been added to a list of countries and regions from which returning Japanese citizens and foreign residents will face harsher quarantine regulations.

"From a prevention standpoint, we would not only prohibit new foreign admission but also returning foreign residents, unless there are exceptional circumstances," Chief Cabinet Secretary Hirokazu Matsuno said at a news conference.

On Nov. 8, Japan lifted its restriction on new foreign entry, allowing businessmen, students, and participants in its technical internship program to enter on the condition that their host firms agreed to supervise their actions.

Kishida stated that the border closure is a "temporary measure" until further information regarding the Omicron variety becomes available, adding that when confronted with an unknown risk, "it is prudent to take all precautions."

Japan will likewise reduce its daily cap for arrivals from 5,000 to 3,500 beginning Wednesday. Japanese people and foreign residents returning to Japan will be obliged to isolate for two weeks, regardless of their vaccination status.

Among the 14 nations and locations affected by the tighter quarantine regulations, tourists who have recently travelled to Angola will be expected to spend the first 10 days of their isolation periods in government-designated institutions.

Concerns are developing about the contagious Omicron variant, which was reported to the World Health Organization (WHO) for the first time last week by South Africa and has since been verified in an increasing number of nations.

On Monday, Japan's confirmed new COVID-19 infections reached 82, in stark contrast with many other nations battling surging cases of the disease.