MANILA (Reuters) - Philippine President Rodrigo Duterte was forced to cut short his attendance of the enthronement of Japan’s emperor on Tuesday, due to what his office said was “unbearable pain” in his lower back after a motorcycle mishap last week.

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The health of Duterte, 74, and his absences from the public spotlight are often the subject of fervent speculation, and the source of complaints from critics that his administration is not forthcoming about the extent of his ailments.

Duterte had a minor fall from a motorcycle in the grounds of his palace last week, causing hip pain, light bruises and scratches on his elbow and knee.

He used a walking cane in Tokyo on Tuesday during a ceremony for Japanese Emperor Naruhito’s ascendancy to the throne, but would skip a banquet to return home and see his neurologist, said presidential spokesman, Salvador Panelo.

“The public can rest assured that there is nothing to worry as regards the physical health and condition of the president as he gives serious priority thereto in actively serving our country,” Panelo said in a statement.

It was the third time this month that the government has tried to allay concerns about Duterte’s health after the maverick former mayor told the Filipino community in Moscow that the frequent drooping of one eyelid was due to a chronic neuromuscular disorder.

Duterte’s known problems include back pain, migraines from nerve damage after a previous motorcycle accident and Barrett’s esophagus, affecting his throat.

His circulation is impacted by Buerger’s disease, from heavy smoking when he was younger. He last year said he had tested negative for cancer.

When missing for longer stretches and amid rumors about deteriorating health, the president’s closest aide has posted on social media what appear to be proof-of-life images of Duterte relaxing at home, often with the day’s newspaper in shot.

His administration attributes his disappearances to fatigue from a punishing daily schedule that typically involves several public events and two or three speeches.

His health is also watched closely because of the political uncertainty that would surround his succession should he be unable to continue.

Duterte’s constitutional replacement would be Vice President Leni Robredo, a political opponent who was elected separately and was not his running mate.