Authorities say at least 78 children and their principal were kidnapped from a school by armed men in northwest Cameroon late Sunday night.
The group was abducted in Bamenda, a commercial hub of Cameroon's restive English-speaking region, on Monday.
A video allegedly of the abductees has been released on the social media by men who call themselves the Amba Boys, an armed group that has been fighting for the secession of the English-speaking Northwest and Southwest, and the creation of a new state called Ambazonia.
An Anglophone separatist movement took up arms past year to demand independence for the North-West and South-West regions - the two English-speaking regions in a country where French is the most widely spoken official language.
In the video, the kidnappers forced about six of the children to give their names and the names of their parents. "You will be going to school now here", say the men who identified themselves as Amba boys.
Biya has promised to pursue policies of decentralisation to address "frustrations and aspirations" in English-speaking regions, his first public acknowledgement of resentments that have spilled over in the country's anglophone Northwest and neighbouring Southwest Region.
Their release comes a day after Cameroon's 85-year-old President Paul Biya was sworn in for a seventh term in office. "That 79 of our children and three of their staff can be picked up by terrorists", Tchoffo said.
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He improved in the last month in confidence and personality. "That's the position I've always played and I feel good there". The title is not something we have to think about now but obviously that has to be the target for us.
One of them shouted, how many times have we asked you not to work here again.
There has been no official statement from the school authorities and as reporters spoke to the parents, a lot of them believed a number of children who had not been kidnapped were being held by the authorities, something that only piles up their frustration.
Some separatists said the government had carried out the kidnappings and framed them to make them look bad.
Others have accused pro-government forces of kidnapping the children in order to sully the separatists' reputation.
The children were taken from a Presbyterian school near the city of Bamenda, which is at the center of an Anglophone separatist movement. But Sunday's involved the largest number of people kidnapped at once, the AP reported.
Separatists have imposed curfews and closed down schools as part of their protest. Witnesses described being beaten, slapped and lectured on the living conditions at the school, before the attackers left with the principal, a teacher, a driver and the students.