Japan has confirmed a new variant of COVID-19, and an infection cluster emerging at a Tokyo immigration facility. The new variant has been found in 91 cases in the Kanto area of eastern Japan and in two cases at airports, chief cabinet secretary Katsunobu Kato said.

The nation has had more than 400,000 cases of COVID-19 with 7,194 fatalities.

Meanwhile, five staff and 39 foreign detainees at a Tokyo immigration facility have tested positive for COVID-19.

All 130 detainees at the facility have been tested for the virus, according to a spokesperson for the Tokyo Regional Immigration Bureau.

None of the cases is serious, and all infected detainees remain quarantined from others.

Japan's detention system for immigration law violators and asylum seekers has been widely criticised for its medical standards, monitoring of detainees and response to emergencies.