The US ambassador to Cameroon on Friday accused government forces of carrying out "targeted killings" and other abuses in the fight against militants demanding independence for two English-speaking regions.
"On the side of the government, there have been targeted killings, detentions without access to legal support, family, or the Red Cross, and burning and looting of villages," Ambassador Peter Barlerin said in a statement.
"On the side of the separatists," he also stressed, "there have been murders of gendarmes, kidnapping of government officials, and burning of schools."
The statement, which adds to warnings by rights watchdogs over abuses in the conflict, was issued after Barlerin met on Thursday with President Paul Biya.
The crisis began in 2016, when activists in the anglophone minority, about a fifth of the country's population of 22 million, stepped up a campaign for greater autonomy.
Biya rejected their demands, prompting radicals to make a full-blown but symbolic declaration of independence last October 1 -- the starting point for armed clashes and a crackdown.
Barlerin, in his statement, called on both sides "to stop the violence immediately."
"I asked the President to use his leadership to encourage both sides to listen to each other," he said. "One cannot have a dialogue until both sides are willing to listen to the other’s point of view."
Many anglophones in the Northwest and Southwest regions complain of marginalisation in education, the judiciary and the economy and having French imposed on them.
The presence of a large English-speaking minority in the centre-west African state dates back to the colonial period.
It was once a German colony that after World War I was divided between Britain and France.
In 1960, the French colony gained independence, becoming Cameroon, and the following year, the British-ruled Southern Cameroons was amalgamated into it under a federal system.
Federalism was then scrapped 11 years later for a "united republic" -- a centralised system that 85-year-old Biya, in power for more than 35 years, has said will not be changed.
According to the International Crisis Group (ICG) think tank, "at least 120" civilians and "at least 43" security forces have been killed since the end of 2016.
On Tuesday, the UN's Office for the Coordination of Humanitarian Affairs (OCHA) said around 160,000 people become internally displaced by the crisis and 20,000 had sought refuge in neighbouring Nigeria.