YAOUNDE/DOUALA, Cameroon (Reuters) - Cameroon saw isolated incidents of unrest in separatist Anglophone regions during voting on Sunday in an election widely expected to extend the rule of President Paul Biya, one of Africa’s last multi-decade leaders.

Polls closed at 1700 GMT after a mostly calm day of voting, but a drive by secessionists to disrupt the election meant not all polling stations were open in English-speaking regions, where voter turnout was low due to security fears.

Tallying the nationwide vote could take up to two weeks.

The army said a regional official suffered a minor injury after his convoy was ambushed by rebels. A security source said at least three armed separatists were shot dead by security forces in the northwest English-speaking town of Bamenda.

The reports could not be independently verified and separatist leaders could not be reached for comment.

Victory for Biya, 85, who has ruled for 36 years, would give him a seventh term, bucking a move by some Africa nations to install presidential term limits. The only current African president to have ruled longer is Equatorial Guinea’s Teodoro Obiang Nguema Mbasogo.

In a speech after casting his vote in the capital Yaounde, Biya did not make specific reference to separatist violence.

“The election campaign took place peacefully,” he said, urging the country to “keep this self-control when the results are out.”

Oil and cocoa producing Cameroon has seen economic growth of over 4 percent a year since Biya was last elected in 2011, but many of its 24 million citizens live in deep poverty.

The secessionist uprising in the Anglophone Northwest and Southwest regions, home to 5 million people, has cost hundreds of lives and forced thousands to flee either to the French-speaking regions or into neighboring Nigeria.

In the English-speaking regional capital of Buea, military snipers kept watch from rooftops on Sunday, part of the army’s response to separatists’ threat to stop the vote.

Two polling stations in Buea visited by a Reuters witness were not operational as staff did not have sufficient electoral materials. Only a few voters were seen casting ballots at other stations in the area and the streets were almost empty.

Biya did not visit the English-speaking regions during his campaign. A central problem of his rule has been his long bid to centralize a hugely diverse population in a country founded in 1961 on the promise of federalism and autonomy for its regions.

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In 2016, protests by Anglophone lawyers and teachers against the marginalization of minority English speakers in their professions led to a heavy-handed clampdown, in which unarmed civilians were shot dead. That radicalized many and armed groups formed in the lush forests of the west.

MONITORING THE VOTE

Some opposition parties have united in an effort to harness discontent about the country’s crumbling infrastructure and about Biya, who they say has ruled Cameroon like a personal fiefdom for too long. The president goes years without convening cabinet meetings and spends long stretches out of the country with his wife Chantal, most often holidaying in Switzerland.

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In 2011, Biya won 78 percent of the vote in an election the United States said was “marked by irregularities”. The odds are still against the opposition, including the main candidate, Joshua Osih of the Social Democratic Front.

Osih urged supporters via Twitter to monitor the count. The authorities have said the election would be free and fair.

“I have come to watch the vote to protect it against theft.” said retired teacher Jean Pierre Tassam, 62, at a polling station in Yaounde where results were being chalked up on a board. “I am worried what the party of power will steal my vote.”

Of the country’s 24 million people, only 6.5 million were registered to vote as of Oct. 1, according to the election authority, reflecting resignation to a continuation of Biya’s long rule. Polling stations were quiet throughout the day even in the capital.

Government spokesman Issa Tchiroma Bakary said the government had taken steps to ensure a smooth election. “It is not impossible that here and there they may be troublemakers,” he told journalists after he voted.

The African Union and other organizations monitored Sunday’s vote, but opposition candidates have already complained of efforts to fix the election in Biya’s favor.