Two Cameroonian opposition parties have agreed to form a coalition in an effort to dislodge six-term President Paul Biya in Sunday's presidential polls.
The announcement on Friday confirms rumours of an opposition manoeuver to try to defeat 85-year-old Biya but the new union will not include the main opposition Social Democratic Front's hopeful Joshua Osih.
Akere Muna, leader of the People's Development Front (FDP) agreed to "withdraw his candidacy ... and to support Maurice Kamto" who is the leader of the Movement for the Rebirth of Cameroon (MRC), Muna's spokesman said in a statement.
On Friday, Kamto's party alleged that a "massive fraud" was under way to ensure the sitting president wins a seventh term.
Kamto's campaign chief Paul-Eric Kingue said efforts to rig Sunday's ballot "had the blessing" of the electoral commission.
"We won't accept any result if this kind of fraud continues," he said at a media briefing by Kamto's MRC in the capital Yaounde.
Cameroon's authorities have long faced accusations of unfairly favouring Biya, one of Africa's longest-serving rulers, who won 78 percent of votes in the polls that took place in 2011.
They were described as "flawed" by observers and the opposition.
Cameroon will place a ban on internal travel by road, rail and air from 17:00 GMT on Saturday until the conclusion of voting.
The borders of the central African nation of 25 million people will also be sealed 48 hours before voting day, according to a decree seen by the AFP news agency.
Kamto's MRC has alleged that polling cards have been forged and that voter registration has continued despite the process being officially closed.
"In 62 percent of areas, the [ruling] Cameroon People's Democratic Movement party is still adding names to the voter roll," said Kingue. "We're not preparing for war, but wherever there is fraud, there will be a firm response."
Communication Minister Issa Tchiroma Bakary said in a statement that "measures have been taken ... to prevent any actions that might create violence or disorder around the elections".
He added that "political figures linked to foreign interests were preparing groups of agitators to stir up violence in the event that the results don't go their way".
The minister did not specify who he was referring to.
"By attempting to spread chaos, they risk being unpleasantly surprised," he said. The authorities would "not tolerate any disorder before, during or after the presidential vote", he added.
Biya has been in power for 35 years and now faces seven opposition contenders following Muna's withdrawal. The opposition frontrunners are Osih and Kamto.
