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Yaoundé - At least 80 inmates in Cameroon's restive English-speaking northwest escaped after gunmen stormed their prison overnight, an informed source told AFP Wednesday.

"There were about a hundred people in the prison and at least 80 have gone," said a source close to security forces in the town of Wum, more than 70 kilometres (45 miles) north of the regional centre Bamenda.

"The gunmen attacked under cover of darkness," the source said, using a ladder to scale the rear wall before battering down the prisoners' cell doors.

English-speaking separatists want to create an independent state, Ambazonia and vow that a presidential election slated for October 7 will not go ahead in their regions.

Eight candidates are running against 85-year-old incumbent Paul Biya, who has ruled the country for 35 years and is seeking a seventh straight term in office.

Separatists say they have suffered years of  discrimination at the hands of the French-speaking majority in Cameroon, and two years of violence in western English-speaking regions have killed hundreds of people and displaced about 200,000.

According to International Crisis Group, 170 members of the security forces and "at least 400 civilians" have died in the conflict. Separatists have not issued a reliable toll.