Cameroon began counting votes after a presidential election on Sunday in which incumbent Paul Biya, the world's oldest ruler at 92, is widely expected to extend his 43-year grip on power despite an energised opposition pushing for change.

His opponents include former government spokesperson Issa Tchiroma, 76, who has galvanised large crowds demanding an end to Biya's long tenure and drawn endorsements from a platform of some opposition parties and civic groups.

However, analysts say that Biya, in power since 1982, is likely to be reelected given his firm control over state institutions and the fragmented nature of an opposition field of nine candidates.

Just over 8 million Cameroonians registered to vote. Results are expected within 15 days, and there are no exit polls.

DECADES OF ECONOMIC STAGNATION

"Nothing is given. Let's wait and see. Let's wait for the name of the winner," Biya told journalists after voting in the upscale Bastos neighbourhood near the presidential palace in the capital Yaounde.

Outside, voters trickled in amid tight security around the president to cast their ballots.

"I hope it will go well, particularly for my champion," said one voter, Patrick Mbarga Mboa, 45, declining to say who he supported. "I hope peace and tranquillity will continue in the country after the election."

Biya's critics are still hoping he can be ousted after decades of economic stagnation and tensions in the Central African nation of 30 million people, an oil and cocoa producer.

"This election comes at a time when the whole nation aspires for change," Tchiroma said after voting in his hometown of Garoua in the North region.

He urged voters to remain vigilant and make sure that the results announced by the constitutional council reflect the result from ballot boxes.

In a sign of rising tensions around the election, a Reuters journalist saw security forces fire teargas to disperse hundreds of Tchiroma's supporters, who tried to gather around his residence in Garoua after the area was cordoned off.

BIYA'S SLOGAN: 'GREATNESS AND HOPE'

Biya abolished term limits in 2008 and has long deployed divide-and-rule tactics. The single-round electoral system gives victory to the candidate with the most votes, even if they have not secured a majority.

"A surprise is still possible, but a divided opposition and the backing of a formidable electoral machine will, we predict, give the 92-year-old his eighth term," said Francois Conradie, lead political economist at Oxford Economics.

"Although we think he isn't very aware of what is going on, it seems that the machine he built will divide to rule one last time," Conradie added in a note.

Under the slogan "Greatness and Hope", Biya has held just one campaign rally, in the northern city of Maroua, relying instead on tightly controlled state media and posts on social media, while his team promises more economic development.

"I want to see change, improvement, maybe a new face. I'm 43 years old. I've never known another president," said Magdalene Tientcheu, who lives in Douala, Cameroon's business hub. "I hope for that. I voted for a new face."