Japan's Emperor Naruhito (Left) and Empress Masako  Photo :AFP

Japanese Emperor Naruhito and Empress Masako have accepted an invitation from Queen Elizabeth II to make a state visit to Britain in early 2020, in what will be their first overseas visit since Naruhito acceded to the throne in May last year.

"Their Majesties the Emperor and Empress will stay at Windsor Castle," said a statement from Buckingham Palace. The visit is planned for "spring 2020," the statement said.

It will be a rare overseas trip by ­Masako, who did not go on many visits with Naruhito while he was the crown princess due to her recovery from a stress-induced ­illness.

"The relationship between our country's imperial family and Britain's royal family has played an important role in fostering strong ties between both of our countries," Japan's Chief Government Spokesman Yoshihide Suga told ­reporters.

"In line with this spirit, the emperor and the empress have received an ­invitation to visit," he said, adding that plans were under way for the imperial couple to visit during the April-June period.

Britain's exit from the European Union, due to take place on January 31, has concerned some Japanese investors and major companies that were encouraged by former prime minister Margaret Thatcher to use the country as a launchpad into Europe.

Elizabeth has hosted two previous state visits from Japan: Naruhito's father Emperor Akihito - who became the first Japanese monarch in two centuries to abdicate when he stepped down in favor of his son last year - made a state visit in 1998 and Emperor Hirohito made a state visit in 1971.

During those visits there were protests by former British prisoners of war who wanted a full apology and further compensation for World War II suffering.

The queen and her husband, Prince Philip, have made one state visit to ­Japan: in 1975 at the invitation of Emperor Hirohito.