President Paul Biya of Cameroon has been re-elected for a further seven-year term with 75 percent of the votes cast, according to official results announced by government.
His two main opponents in Monday's presidential election, John Fru Ndi and Adamou Ndam Njoya, have accused the government of massive vote rigging and have appealed to the Constitutional Council to annul the entire poll.
A team of 1,200 monitors deployed by the Roman Catholic Church in Cameroon also denounced widespread fraud.
However, observer teams sent from the United States and the International Organisation of French-speaking Countries (OIF) said they were reasonably satisfied with the conduct of the election.
Interior Minister Marafa Hamidou Yaya, told reporters on Thursday that with only a handful of remote polling stations yet to report, it was clear that Biya had won the election with 75.24 percent of the votes cast.
The 71-year-old head of state, who rarely appears in public, has ruled this West African country of 16 million people since 1982.
Fru Ndi, the leader of the Social Democratic Front opposition party, who draws strong support from the Anglophone highlands of southwestern Cameroon, was in second place with 17.13 percent, Yaya said.
Ndam Njoya, a former minister and diplomat who stood on behalf of a coalition of nine opposition parties called the Coalition for National Reconciliation and Reconstruction, trailed third with 4.71 percent, he added.
The interior minister claimed that nearly 80 percent of Cameroon's registered voters had turned out to cast a ballot, dismissing press reports that the number of people observed queuing at polling stations was generally very low.
Fru Ndi, who was officially credited with 35 percent of the vote when he first stood against Biya in 1992, claimed to have won the latest election.
"Partial results in our possession show the SDF candidate leading by 45 percent. Mr Biya of the CPDM (Cameroon People's Democratic Movement) has 39 percent," Fru Ndi told IRIN on Friday.
"Several persons voted more than once, ballot boxes were stuffed with ballot papers, our observers were beaten and driven from polling stations in almost all parts of the country," he complained.
Ndam Njoya denounced the election as "a masquerade."
The Yaounde French language daily newspaper Le Messager meanwhile cast doubt on the independent credentials of the US observer delegation which had strongly endorsed the poll.
Under the headline "Biya buys American observers," it said the members of the US delegation were stooges recruited by the US lobbying firm Patten & Boggs to endorse the election result.
Le Messager said the government had paid Patten & Boggs US$400,000 to send over a team of US monitors who would report favourably on the conduct of the poll in view of the critical judgements issued by independent US observers who were present at the previous two presidential elections in 1997 and 1992.
The newspaper noted that only one member of the team led by former Texas senator Greg Laughlin had actually been to Africa previously.
"The elections were conducted fairly," Laughlin told the BBC. "We have never seen such a transparent way to show who got the vote."
Norbert Ratsirahonana of Madagascar, the leader of the OIF observer team said the election was well organised and voting had taken place smoothly. But he added that opposition candidates had lacked fair access to the media during the campaign, and that there was a dispute about how the electoral lists had been drawn up.
Ratisirahonana also noted that some of the indelible ink used to mark voters' fingers had washed off easily.
A Commonwealth observer team, led by former Canadian prime minister Joe Clark, was due to give its own verdict on the election in a departure statement on Saturday.