Passengers wait in a line to receive PCR test kit at quarantine counter of the airport on their arrivals at Kansai International Airport in Osaka, western Japan, Tuesday, Nov. 30, 2021.AP
The announcement came as authorities announced they had detected a second infection with the new strain in an arriving traveler, a day after confirming a first case.
"We have asked airlines to halt accepting all new incoming flight reservations for one month starting December 1," a transport ministry official told AFP, adding that existing bookings would not be affected.
Japan's government has already tightened its tough border measures, banning entry of all non-citizens coming from 10 southern African nations.
Quarantine measures have also been toughened for citizens and foreign residents coming from several dozen more countries and territories over virus fears.
Japanese officials said a second case of Omicron was confirmed on Wednesday in a traveler arriving from Peru who entered the country last month.
The first case, announced Tuesday, involved a man arriving from Namibia.
Japan's borders have been virtually sealed throughout most of the pandemic, with even residents barred from entry for part of 2020.
The border measures have been a key part of the country's Covid response, which has not involved the tough lockdowns seen in some parts of the world.
After a summer surge in cases, Japan is registering only double digit infections nationwide most days, and has logged around 18,360 deaths during the pandemic.
Around 77 percent of the country's population is now fully vaccinated, and booster shots began being administered on Wednesday to people who received their second dose at least eight months ago.