Human Rights Watch has accused Cameroon's armed forces of taking part in the killing of at least 21 civilians this month in a region where troops are battling anglophone separatists.

In a statement on Tuesday, the US-based rights group said 13 children and one pregnant woman were killed by government forces and armed Fulani herders in Ngarbuh village on February 14.

More:

They also burned five homes, pillaged a large number of other properties and beat residents, HRW reported.

"The killings were so outrageous, the abuses so blatant and evidence so damming. The killings were deliberate and were aimed at punishing the population suspected of harbouring and collaborating with the separatists," said Ilaria Allegrozzi, HRW's senior Africa researcher.

"The gruesome killings of civilians, including children, are egregious crimes that should be effectively and independently investigated, and those responsible should be brought to justice."

The incident occurred in a remote part of the Northwest region - one of two English-speaking regions gripped by conflict sparked by demands for independence from majority-Francophone Cameroon.

The army says there were only five civilian deaths, which it said happened when fuel containers exploded in a firefight.

The government has denied what it called "outrageous and misleading allegations".

'Maximum pressure'

On Monday, hundreds of pro-government demonstrators, holding placards and chanting slogans, gathered outside the French embassy in Cameroon to protest against what they described as Paris's intervention in the country's affairs.

This came after remarks by French President Emmanuel Macron on Saturday that he would put "maximum pressure" on Cameroonian President Paul Biya over separatist conflicts in Cameroon's English-speaking regions.

"I am putting maximum pressure on [Cameroon's President] Paul Biya so that he deals with the crisis in the anglophone regions and that he treats the political opposition with respect and he eventually freed opposition leader Maurice Kamto," Macron said in a widely shared video on social media

"We are seeing that the situation is deteriorating and I will call him so that the intolerable situation ceases."

Angered by Macron's remarks, one protester in the capital Yaounde said: "Who is this young 40-year-old who is trying to teach a lesson to our old president? Look what they have done to Libya, Ivory Coast and Mali ... They are not going to mess with us."

English speakers account for nearly one-fifth of Cameroon's population of 24 million, who are majority French-speaking.

Years of grievances at perceived discrimination against English-speakers snowballed into a declaration of independence in the anglophone regions in October 2017, which was followed by a government crackdown.

The declaration has not been recognised internationally and Biya, in power for 37 of his 87 years, has refused demands to return to a federal system.

However, the government has lately decentralised some of its powers after a "national dialogue" on the anglophone crisis which was boycotted by the separatists.

More than 3,000 people have died and at least 700,000 have fled their homes in the nearly 29-month-old unrest. Rights monitors say abuses have been committed by both sides.