Tokyo: Japan's NHK national television said the country's transport ministry on Wednesday requested international airlines to stop taking new reservations for all flights arriving in Japan until the end of December.
The ministry made the request as an emergency precaution amid growing concerns over a new variant of the coronavirus, NHK reported.
Those who have already made reservations are not affected.
The move comes as Japan confirmed a second case of the new coronavirus variant - known as omicron - in an arrival from Peru, one day after it reported its first case on Tuesday following genetic sequencing on samples taken from a Namibian diplomat.
Meanwhile, Japan on Wednesday started offering coronavirus vaccine booster shots to health care workers amid growing concerns over a new variant of the virus that has already been detected in the country.
Japan's initial vaccination drive kicked off in mid-February and some medical workers who received jabs more than nine months ago are now eager to get additional protection ahead of a possible next wave of infections.
At Tokyo Medical Centre, a group of nurses and doctors received booster shots.
"It's an important first step for our patients and their families to be treated with a sense of safety," said hospital chief Kazuhiro Araki.
Even though vaccine efficacy against the new variant is still being examined, booster shots are important, Araki said, because the vaccines remain effective against other strains of the virus, including delta, which put heavy pressure on Japan's health care systems this summer.
In principle, those who received their second shot eight months ago are eligible for a third shot to prevent breakthrough infections. Eligibility may be shortened to six months if there is a resurgence of infections, officials said.
Japan's vaccination rollout got off to a slow start but surged from late May onward and now about 77% of the population has been fully vaccinated - a main reason experts cite for Japan's steady slowing of infections since September.
Booster shots for elderly people, who received their initial inoculations starting in April, are expected to begin in January.