Japan's Emperor Akihito declares the start of the new parliament session at the Upper House in Tokyo, Japan, September 26, 2016. REUTERS/Kim Kyung-Hoon

TOKYO (Reuters) - Japanese Emperor Akihito, 82, has a cold and fever and has canceled morning duties, an official at the Imperial Household Agency said on Friday.

The emperor has no planned duties Friday afternoon and this weekend and will rest at the Imperial Palace, the official said.

In August, Akihito said he worried that age may make it difficult for him to fully carry out his duties, remarks widely seen as suggesting he wants to abdicate, a step unprecedented in modern Japan and not possible under current law.

There are four male heirs including 10-year-old Prince Hisahito, the emperor’s only grandson. The three older heirs are Akihito’s 80-year-old brother and his two middle-aged sons including Crown Prince Naruhito.

Akihito, who has had heart surgery and been treated for prostate cancer, was also diagnosed with influenza in February.

Empress Michiko, 82, was diagnosed with acute bronchitis early this month but has recovered and returned to her duties.