Cameroon's influential Catholic Church has called for calm, as fears grow that violence could erupt once official results from the presidential election are declared.

Opposition candidate and ex-government spokesman Issa Tchiroma Bakary has declared himself the winner of the 12 October election, saying he defeated 92-year-old President Paul Biya, who is seeking to extend his 43 year-rule by seven more years.

Tchiroma's declaration was criticized by both the government and Biya's ruling party, with several officials describing it as illegal.

Cameroon's Constitutional Council has not yet released the final results.

It has until 27 October to declare the winner.

Tchiroma's defiance and promise to defend what the 76-year-old calls his victory has raised fears of violence in the central African nation.

In a statement released by the National Episcopal Conference of Cameroon (NECC), Catholic Bishops expressed the need for peace and stability.

The clerics said they hoped that the official result would reflect the will of the electorate, and "nothing will be changed by any authority involved in this exercise".

The Catholic Church is highly respected and is viewed as a moral voice of the nation.

Its statement echoes the sentiments of many, who have urged the Constitutional Council to ensure that the result is not rigged.

Some of the Church's prelates have been outspoken in their criticism of Biya and how he has governed.

In January, Monsignor Yaouda Hourgo, Bishop of the Diocese of Yagoua in the Far North region, said it was preferable for the "devil" to take power, rather than for Biya to seek re-election.

"We're not going to suffer any more than this. We've already suffered enough," he said in his homily.

Following protests over alleged fraud, the Constitutional Council said it would begin hearing complaints on Wednesday. Its verdict will be crucial in determining who will be the next president.

In a message to the judges, the Catholic Bishops reiterated a simple message: "The truth shall set you free."