They warned that if their demand was not met, their supporters would take to the streets in protest.
The candidates, including John Fru Ndi, leader of the main opposition party and Adamou Ndam Njoya of the CDU party, rejected the yet to be announced results, saying no winner will be legitimate due to irregularities during the vote.
Incumbent President Paul Biya is widely expected to be re-elected in the one-round poll, contested by more than 20 rivals from the splintered opposition.
The candidates blamed Cameroon’s elections management body Elecam for what it said were irregularities and for failing to organise free and fair elections.
“We therefore reject any result that shall be declared by the Constitutional Council because of our well-founded conviction that there were really no elections in Cameroon on the 9th of October 2011,” the candidates said in a statement.
“Should the council refuse to annul this counterfeit election and insist on declaring a result, we hereby call on the people to come out massively to demonstrate,” they said.
Cameroon is the world’s fifth largest cocoa producer and the region’s breadbasket, supplying food to Chad, Central African Republic, Congo Republic and Gabon. It also hosts the Chad-Cameroon crude oil pipeline.
But its economic growth has underperformed some of its neighbours, and the media and opposition have criticised Biya for lax governance that has allowed corruption, red tape and nepotism to fester.