President Paul Biya, in office since 1982, vows to end a crisis that has killed more than 400 people in the central African nation's Southwest and Northwest territories in more than a year.

The fractured opposition has been unable to rally behind a strong challenger to the 85-year-old leader.

Voting ended around 6pm local time on Sunday and results are expected within two weeks.

"I am satisfied after performing my civic duty and particularly satisfied that the election is taking place in calm and serenity and without fighting," Biya said after voting.

"I hope that the calm will continue after results are proclaimed."

Main opposition Social Democratic Front party candidate Joshua Osih voted in Douala and called for transparency in vote counting.

"My wish is that the results of the ballot should not be tampered with," he said.

"That transparency should be the watchword and that the choice made by the Cameroonian people be respected," he said.

Even as the candidates spoke, violence had already marred the voting.

Gun fighting between the military and separatists began on Saturday in at least six towns and villages including Nkambe, Mamfe and Kumbo.

The military killed a number of armed men in the English-speaking Northwest and Southwest regions, officials confirmed.

More than 200,000 people have been displaced because of violence by both separatists and the military in the Northwest and Southwest, with many towns simply abandoned.

By law, voters can only cast a ballot in the community where they are registered.

All voters in the English-speaking regions had to be screened, and present voter's cards and identity cards before they were able to cast their ballots. Numbers were low at the start of the vote on Sunday.

In the French-speaking regions, however, thousands lined up eager to vote.

Australian Associated Press