Crown Prince Naruhito will take over Emperor Akihito's constitutional duties while his father has surgery for prostate cancer and undergoes rehabilitation, the government said Tuesday.

The government decided at a Cabinet meeting to transfer the duties, including the Jan. 20 convening of the 156th ordinary Diet session, government officials said.

The Emperor was to attend an annual New Year's poetry reading at the Imperial Palace on Wednesday, as scheduled.

On Thursday morning, the 69-year-old Emperor will authorize the transfer of his constitutional duties to his 42-year-old son shortly before entering University of Tokyo Hospital to prepare for his operation, which is scheduled for Saturday.

Government officials said the Emperor will recuperate at the Imperial Palace for an extended period after being discharged from the hospital and will be away from official duties for more than a month.

The Emperor has entrusted his elder son with constitutional duties on 10 previous occasions when he has made overseas trips. He himself took over constitutional duties for Emperor Showa from September 1987 when his father was incapacitated due to illness.

The Emperor was diagnosed with prostate cancer in a medical checkup last month.

Cancer cells were detected in a tissue sample taken from the Emperor's prostate in a biopsy at the Hospital of the Imperial Household, but his cancer is a well-differentiated tumor and will not spread to other parts of his body.