The government is set to extend the COVID-19 quasi-state of emergency in Tokyo and 14 prefectures as Japan has been facing a slower-than-expected fall in infection numbers due to the highly contagious Omicron variant, officials said Wednesday.

The measures, under which restaurants and bars are required to close early and stop or limit the serving of alcohol, will likely remain in place until March 21, the officials said. The government will formally decide on the extension after consulting with a panel of health experts on Friday.

The 14 prefectures include Osaka, Aichi, Hokkaido as well as the three areas neighboring Tokyo -- Chiba, Kanagawa and Saitama.

Currently, 31 out of the nation's 47 prefectures are under a quasi-emergency, which can be more limited in terms of coverage and restrictions than a full state of emergency.

The government will lift the measures in 11 prefectures while it remains undecided on the remaining five, according to the officials.

"Infection levels are still high in urban areas and we haven't seen much improvement trend in the countryside," health minister Shigeyuki Goto said at a meeting of medical experts.

Japan's top coronavirus adviser Shigeru Omi has said a slow rollout of booster vaccine shots is one of the reasons behind infection cases remaining high.

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