The government is considering giving Emperor Akihito the title of "joko," an abbreviation of "daijo tenno," meaning retired sovereign, should he abdicate, sources said Thursday.

To avoid powers being split between the Emperor, if he abdicates, and his successor, an advisory panel to the government of Prime Minister Shinzo Abe is expected to discuss what official role he could play in the future, according to the sources.

Historically, retired emperors have taken such titles as "daijo tenno" and "joko." But no emperor has relinquished the throne since Emperor Kokaku in 1817, and the current law on Imperial affairs has no provisions for abdication and so no rules on what a retired emperor should be called.