Japanese will tune in to Emperor Akihito's rare video message on Monday following reports that he would abdicate in the next few years.

In the pre-recorded message, the 82-year-old monarch will talk about his duties as a "symbol emperor" as stipulated by the constitution, palace officials said.

He will most likely avoid the explicit expression of abdication, which would involve political and legal procedures that he is not allowed to discuss.

The emperor still works, though his aides have shifted some of his duties to Crown Prince Naruhito - the elder of his two sons and most likely successor.

Yet he has referred to his old age in recent years, admitting to making small mistakes at ceremonies. During the August 15, 2015, anniversary of the end of the Second World War, he started reading a statement when he was supposed to observe a moment of silence.

After the initial surprise, the public warmly welcomed the reported abdication plan, saying the hardworking emperor deserves to enjoy his long-overdue retirement.

According to a nationwide telephone survey by Kyodo News agency this month, nearly 90% of the respondents said Akihito is given too much work, while more than 85% said an abdication should be legalised as an option for him and his successors.

The emperor has reportedly told palace officials and his family that he does not wish to cling to his title with drastically reduced responsibility or by arranging a substitute, and his two sons have accepted the idea.

The quiet discussion reportedly started about five years ago, around the time he had health problems - he was in hospital with bronchitis in 2011, and had heart bypass surgery in 2012.

Palace officials quickly denied the report, because the emperor is not supposed to say anything that would cause a change to the existing system, including his constitutional status.

He ascended to the throne in 1989 after the death of his father, Hirohito, who was considered a deity until Japan's defeat in the Second World War, fought in the name of the emperor.

Akihito brought the cloistered imperial family closer to the public and broke with other traditions, including his marriage to a commoner. He has repeatedly said he respects Japan's postwar pacifist constitution and is committed to his status as the symbol and the unity of the people, not the sovereign.

Some speculate that his abdication may be an attempt to put a brake on Prime Minister Shinzo Abe's plan to rewrite the constitution.

Mr Abe and his ultra-conservative supporters want to scrap a part of the war-renouncing article and upgrade the emperor to the sovereign again.

AP