Armed men kidnapped 79 children from a school in western Cameroon on Monday and a local pastor said separatist militias were responsible.

The abduction happened before dawn in the city of Bamenda in the English-speaking Northwest region. The children, their principal and a driver were taken into the bush outside town, military and government sources said, and the army had started searching the area.

Anglophone secessionists have imposed curfews and closed schools as part of their protest against President Paul Biya's French-speaking government and its perceived marginalisation of the English-speaking minority.

A separatist spokesman denied involvement in the kidnapping.

'In total 81 people were kidnapped including the [school] principal. They were taken to the bush,' a military source told Reuters.

An army spokesman confirmed the abduction but declined to say how many were taken. He said it was most likely to have been carried out by separatists. The separatist spokesman blamed government soldiers.

Samuel Fonki, a reverend for the Presbyterian Church in Cameroon, told Reuters that he is moderating for the release of the children. He said the separatists were responsible.

'They say I have to close the school. They asked for a ransom,' he said, though no amount was specified.

Samira Daoud, Amnesty International's West and Central Africa deputy regional Director, said: 'In a case with a chilling echo of the 2014 kidnappings of the Chibok schoolgirls in Nigeria, it is vital that Cameroon's government act swiftly and decisively to reunite these children with their loved ones.

'We express solidarity with the families of these children and demand that the Cameroon authorities do everything in their power to ensure all the pupils and school staff are freed unharmed.'

UNICEF said the organisation 'strongly condemns the reported attack and calls for the immediate and unconditional release of all the children abducted'.

The separatist movement gathered pace in 2017 after a government crackdown on peaceful demonstrations. One of the original gripes was that French-speaking teachers were being deployed to English-speaking schools in the Northwest and Southwest regions.

Violence intensified in 2018, including during an army crackdown in which civilians were killed. Many people have fled Bamenda and other centres to seek refuge in more peaceful Francophone regions.

US missionary Charles Wesco was shot dead last week in a suspected attack by separatists on his way to Bamenda.

Additional reporting by Reuters.