(File photo: social media)

Japan's Prime Minister Shinzo Abe will address speculation over his health at a press conference later Friday, with reports suggesting he will say he is fit to stay in office.

Questions about Abe's health have been swirling since he made a previously unannounced visit to hospital for medical checks on August 17, and then returned for further checks a week later, on Monday.

Abe, 65, ended his first term as prime minister after just a year in the job, in part due to crippling health problems later diagnosed as ulcerative colitis.

Even before the recent hospital visits, there had been reports claiming the prime minister was vomiting blood, as well as questions over his limited public appearances and decision to avoid holding a press conference to address criticism of his handling of the coronavirus.

Japanese government spokesman Yoshihide Suga has attempted to dismiss the speculation, repeating Friday that Abe remained in good health.

"In terms of the prime minister's health, the prime minister himself has said he wishes to work hard and I see him every day and feel that there is no change in his condition," Suga told reporters at a regular press conference.

On Thursday, Suga told Bloomberg News that Abe would "of course" be able to serve out the rest of his term, which lasts until September 2021.

"He'll be all right," he said.