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 Prime Minister Shinzo Abe
Japan's Prime Minister Shinzo Abe has faced growing speculation about his health in recent weeks. Photo: AFP / Kazuhiro NOGI

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.

Japanese Prime Minister's Shinzo Abe's profile
Profile of Japan's Prime Minister Shinzo Abe. Photo: AFP / Janis LATVELS

Analysts said it now looked likely Abe would seek to stay on through the end of his term as leader of the ruling Liberal Democratic Party, which ends in September 2021.

"What is clear is that Abe's health is not in good shape," Mikitaka Masuyama, a professor of politics at the National Graduate Institute for Policy Studies, told AFP.

"But I think he will stay in office while managing his illness," Masuyama said, noting that Japan has been able to keep its coronavirus outbreak relatively contained and Abe retains reasonable public support.

"Even though public support has fallen sharply, levels above 30 percent are not bad for a Japanese prime minister," he said.

Abe's health woes come at a bad time for the prime minister, who this week broke the record for the longest uninterrupted stint in office in Japanese history.

Despite the relatively contained impact of coronavirus in Japan, Abe's government has been heavily criticised for its approach to the crisis, including a U-turn on stimulus payments and a much-mocked decision to issue each household two cloth face masks.

The prime minister has also seen his signature "Abenomics" economic policy come under increasing strain, with the country already slumping into recession even before the coronavirus crisis hit.

Still, experts say there is little appetite within the LDP for Abe to depart early, especially as there is no consensus yet on his successor.

And with Japan's fragmented opposition so far unable to capitalise on the government's falling approval ratings, there is little pressure on Abe to step aside.

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