Japan has said it will shut its borders to foreigners to prevent the spread of the Omicron variant of the coronavirus, Reuters reports.

Japan will bar entry to foreigners from midnight and Japanese returnees from specified nations will have to quarantine in designated facilities, Prime Minister Fumio Kishida told reporters.

"These are temporary, exceptional measures that we are taking for safety's sake until there is clearer information about the Omicron variant," Kishida told reporters. "I'm prepared to bear all criticism from those saying the Kishida administration is being too cautious."