The government is considering postponing a state visit by Emperor Naruhito and Empress Masako to Britain scheduled for this spring due to the coronavirus pandemic, according to a source.
It would have been the first overseas trip by the imperial couple since the emperor's enthronement in May.
The government is putting off a plan to send senior officials of the Imperial Household Agency to Britain late this month as part of preparation for the visit.
"It will be best for the emperor and empress to make their trip in conditions preferable to both Japan and Britain," the source said.
Buckingham Palace said in January that the couple had accepted an invitation from Queen Elizabeth II to make the visit.
Officials in Tokyo said earlier the visit would likely take place between April and June.
The emperor and empress were scheduled to stay at Windsor Castle, 34 kilometers west of London, where the queen usually spends her private weekends.
Expectations have been high in Japan for new imperial diplomacy, as Emperor Naruhito is the first reigning sovereign to have studied abroad, at Britain's University of Oxford. The empress meanwhile is a former diplomat educated at Harvard and Oxford.