YAOUNDE (Reuters) - Cameroonian President Paul Biya has won re-election by a landslide, official results showed on Monday, extending his 36-year rule despite claims from two leading opposition candidates that the vote was fraudulent.

At 85, Biya is the oldest leader in sub-Saharan Africa and the victory cements his place as one of Africa’s longest-serving rulers. Most Cameroonians have known only him as president.

But looming over his victory are allegations of ballot stuffing and intimidation, while turnout was low because of a secessionist uprising in the Anglophone Northwest and Southwest regions in which hundreds, including unarmed civilians, have died over the past year.

Biya won 71 percent of the vote on a turnout of 54 percent, according to figures announced by the Constitutional Council. He won strongly in nine of 10 regions, including the South and East where he took more than 90 percent of the vote. His closest rival, Maurice Kamto, won 14 percent overall.

“Thank you for your renewed and large confidence,” Biya said on Twitter. “Let us now join in taking up, together, the challenges that confront us.”

The announcement follows two weeks of tension in the coffee- and oil-producing country where, despite economic growth above 4 percent a year since the last election, most people live in poverty.

Kamto claimed victory for himself on Oct. 8 based on his campaign’s figures, and in recent days police silenced opposition marches in the port city of Douala where he is popular.

FILE PHOTO: President of Cameroon Paul Biya with Chinese President Xi Jinping (not pictured) attend a signing ceremony at The Great Hall Of The People in Beijing, China March 22, 2018. Lintao Zhang/Pool via Reuters/File Photo

“We solemnly and categorically reject these manufactured results and refuse to recognize the legitimacy of the Head of State,” Kamto said in a statement. “We will use all means of law to restore the truth of the ballot box.”

Third-placed candidate Cabral Libii also rejected the results, saying they did not “reflect reality” in Cameroon.

Authorities have defended the voting process. “The election was free, fair and credible in spite of the security challenges in the English-speaking regions,” the President of Constitutional Council, Clement Atangana, said on Monday.

STRUGGLE FOR SECESSION

The secessionist movement began in reaction to a government clampdown on peaceful protests calling for an end to the marginalization of Cameroon’s English-speaking minority. Police killed civilians, sparking further protests.

The army burned villages and killed unarmed civilians, residents told Reuters, forcing thousands to flee to French-speaking regions or neighboring Nigeria. Ghost towns are all that remain of once vibrant cities in those regions.

Turnout was 5 percent in the Northwest and 16 percent in the Southwest. In an area of 5 million English speakers, less than 100,000 voted.

Despite the unrest, and a desire among the young for change, the opposition appeared unable to mount a credible challenge to Biya who, despite long absences in Switzerland, has kept core support. He has also benefited from apathy from many who saw no point in voting.

“I voted for the opposition even though I did not trust them. I wanted anything but Paul Biya,” said Jerome, an unemployed 32-year-old. “My three children will have no future as long as he is there.”

The only current African president to have ruled longer than Biya is Equatorial Guinea’s Teodoro Obiang Nguema Mbasogo.