Cameroon's 91-year-old president, Paul Biya, is in good health, the government said on Tuesday in a statement, calling widespread reports saying otherwise "pure fantasy."

Biya has not been seen in public since attending a China-Africa forum in Beijing in early September. His failure to appear as scheduled at a summit in France last weekend stoked speculation that the nonagenarian was unwell.

"Rumours of all kinds have been circulating through the conventional media and social networks about the president's condition," government spokesperson Rene Sadi said in the statement. "The Government unequivocally states that these rumours are pure fantasy ... and hereby issues a formal denial."

Opposition parties and civil society groups have been calling for an update on the status of Biya's health and his exact whereabouts.

After Beijing, Biya paid a private visit to Europe, Sadi said. "The head of state is in good health and will be returning to Cameroon in the coming days."

With no clear succession plan, Biya's death would bring more political turmoil to West and Central Africa, which has seen eight coups since 2020 and several other military attempts to overthrow governments.

His recent absence from the meeting of leaders from French-speaking countries in Paris was much remarked on at the two-day event, according to three non-Cameroonian African ministers who attended.

"He's over 90, he hasn't been involved in day-to-day business for a long time, but if he dies, the situation is likely to get out of hand," said one of the ministers, speaking on condition of anonymity.

"No one has prepared for the aftermath. We don't know what Cameroon (would) be like without Paul Biya."

Cocoa and oil-producing Cameroon, which has had just two presidents since independence from France and Britain in the early 1960s, is in the grips of a secessionist war that has killed thousands and a violent Boko Haram insurgency in the north.