It would be "difficult" for Crown Prince Naruhito to begin his reign as emperor on Jan. 1, 2019 — a plan recently reported by media outlets — due to key events held every year on New Year's Day, a senior Imperial Household Agency official said Tuesday.

Citing unnamed sources, media reports said the government is considering arranging for the Crown Prince, 56, to ascend the throne on Jan. 1, 2019, following Emperor Akihito's abdication the previous day.

Emperor Akihito has hinted publicly of his desire to retire, citing his advanced age.

Vice Grand Steward Yasuhiko Nishimura told a news conference, however, that Jan. 1 "is an important day for the Imperial family."

"It would be difficult to set events related to an abdication," he added.

He cited the New Year's celebration at the Imperial Palace, which is defined as a "matter of state," and various Shinto rites, which are private acts of the Imperial family.

Noting that he was making his remarks "in general terms," Nishimura said that, "I believe it is better to clarify the Imperial Household Agency's view" as stories about the 2019 plan have been widely reported.

During a news conference last week, Nishimura said he was surprised by the news, calling it "a bolt from the blue."

Prime Minister Shinzo Abe's government has regarded 2018 as a time limit after the 83-year-old Emperor Akihito alluded to the timing in a video message last August.

"A major milestone year marking the 70th anniversary of the end of World War II has passed, and in two years we will be welcoming the 30th year of Heisei," the Emperor said.

The government is reportedly seeking to enact special legislation during a Diet session convening Friday to enable the Emperor to abdicate.