A Zimbabwean priest has been arrested for claiming that President Robert Mugabe, who turns 93 next month, will die in October.

Pastor Patrick Mugadza was arrested on Monday (16 January) in the capital of Harare, in the northeast of the country.

His lawyer Gift Mtisi told AFP that Mugadza had been in Harare's magistrate court for another suspected crime, when police officers detained him for his remarks about Mugabe's age.

"He was appearing at the court on a different matter when police arrested him during a break and charged him over the prophecy," Mtisi said.

"He was initially charged with undermining the authority of the president and the charge was later changed to insulting people of a certain race or religion."

Mugabe has been in power since Zimbabwe – formerly Rhodesia – gained independence from British colonial rule in 1980. However his condition has significantly deteriorated in recent years, sparking speculation about his health.

He has also made frequent visits to the Far East for medical treatment, which have compounded concerns about how long his reign will last.

Despite such concerns, and no clear indication as to who will succeed Mugabe upon his death, talking about the issue in Zimbabwe is taboo and frowned upon. His ZANU-PF party has been riven by factional fights between camps angling to succeed him.

A law that forbids "undermining the authority of or insulting the president" is also in place.

However, some private media outlets have taken large risks in broadcasting various clips where Mugabe has stumbled or fallen, potentially demonstrating his weakening nature.