British Airways is operating to Tokyo via South Korean capital Seoul to avoid having crew stay overnight in Japan amid the continuing crisis in the country.
Passengers booked to travel to and from Tokyo up to March 31 can claim a refund, re-book for a later date or choose to fly to another destination. Those booked up to April 10 may also re-book or switch destinations.
BA said it continues to review the situation daily, amid reports that all aircraft flying into and out of Tokyo are being checked for radiation.
However, BA said it was following the advice of the World Health Organisation and International Civil Aviation Organisation (ICAO) that there is no medical basis for restrictions on flying to and from Japan and that it is not necessary to screen passengers.
BA operates 12 services a week between Heathrow and Tokyo – flying daily into Narita airport and five times a week to Haneda, a service launched only last month.
The airline advises any passenger due to travel to Tokyo to check the status of their flight before departing for the airport.