TOKYO: Japan's government is planning legal steps that would allow Emperor Akihito to abdicate and his son to ascend the throne in two years, media reported on Wednesday, potentially setting the stage for the first abdication in two centuries.

Japanese Emperor Akihito (83), hinted in August that he wanted to abdicate, saying he worried that age might make it difficult for him to carry out his duties fully.

Once considered divine, the emperor has no political power, but is defined in the constitution as a symbol of the state and the unity of the people. Under current law, abdication is not possible.

However, reports in all of Japan's mainstream newspapers including the Nikkei, said the government was considering steps that would allow Akihito to abdicate and for 56-year-old Crown Prince Naruhito to ascend the throne on January 1, 2019.

The abdication itself would take place on December 31, 2018, or January 1, some reports said.

Akihito, who has had heart surgery and been treated for prostate cancer, said in August that 2018 would mark his 30th year on the throne, which was taken as a tacit expression of when he would like to step down.

He ascended the throne after the 1989 death of his father, Hirohito, in whose name Japan fought World War Two, and has worked to heal the wounds of the conflict in Asia during trips overseas.

A panel of experts that began discussing the issue of his potential abdication late last year is expected to make recommendations later this year. The government could submit a special law to parliament on abdication as early as this spring, the reports said.

Chief Cabinet Secretary Yoshihide Suga said on Wednesday that he was unaware of any such development and declined to comment, citing the ongoing discussions.

Opinion polls show a majority in favour of allowing abdication. But, media reports say there would be unsufficient time to prepare by 2018.

The reports said that pinning the change to January 1, 2019 would minimise inconvenience due to the Japanese custom of "reign names" that take effect as soon as an emperor ascends the throne and enumerate how long he has reigned. Akihito's reign name is "Heisei" and this year is Heisei 29.

Shares in printing companies skyrocketed on Tuesday in anticipation of the printing needs required by a new reign name, with Nozaki Insatsu Shigyo Co Ltd surging 32.8 percent, but most had trimmed gains by noon on Wednesday.