TOKYO (AFP) -- Japan could pass a one-off bill allowing its retirement-ready emperor to step down, a government panel said Monday, in what would be the first abdication in over two centuries.

The option was one of several presented by the group of experts charged with sorting out the thorny issue. They are expected to make a final recommendation in March.

Last summer, Emperor Akihito, 83, expressed a desire to abdicate after nearly three decades on the Chrysanthemum Throne, one of the world's oldest monarchies, citing his advancing age and weakening health.

The news sent shockwaves across Japan and unleashed a flood of questions.

Japan has had abdications in its long imperial history, but the last one was over 200 years ago and there is no mechanism for one under current laws.

On Monday, the six-member panel, which was tapped to find the best way forward, said other options include revising the law to allow future emperors to resign if they choose, reducing Akihito's official duties, or letting him become a regent instead of abdicating.

"This is a very serious issue and we need to discuss it carefully," said Prime Minister Shinzo Abe, who attended the panel's meeting.

Abdication is a sensitive issue in light of Japan's modern history of war waged in the name of Akihito's father Emperor Hirohito, who died in 1989.

Some scholars and politicians worry the issue could open a can of worms and risk Japan's monarchs becoming subject to political manipulation. Under the constitution they play only a symbolic role.

The leading opposition Democratic Party opposes a one-off change, arguing this would not ensure stable future successions. It has advocated a revision to the permanent law that governs the imperial family.

Japanese media have previously reported that the government is planning for Akihito to retire and be replaced by his eldest son, Naruhito, on Jan. 1, 2019.