Bouba Samson was abducted in August by suspected English-speaking separatists, who later contacted his wife to demand payment to free him.

The Cameroonian authorities have not commented on the case.

Jacques Bessala Ngono, spokesperson for a 20,000-strong teachers' body, the Collective of Outraged Cameroonian Teachers, told BBC Afrique:

Quote Message: This is about freeing a human being who is the hands of people who could kill him at any moment.

Quote Message: Let's not forget that at teacher was decapitated in Bamenda a few months ago which has traumatised us on a national level."

Abductions are increasingly common in Cameroon where school children have become pawns in the fierce conflict between Cameroon's mainly French-speaking government and separatist fighters demanding independence for the country's English-speaking heartlands.

The separatists are enforcing a lockdown across cities, towns and villages in the North-West and South-West regions to ensure schools remain shut for a fourth academic year in a row.