The anglophone Northwest and Southwest regions have been gripped by conflict since the separatists declared their independence in October 2017 after decades of grievances at perceived discrimination by the francophone majority.
The main separatist leader and self-proclaimed president of "Ambazonia" -- the name given to the breakaway state -- Julius Sisiku Ayuk Tabe said that the negotiations started with government representatives on Thursday evening.
"Nine of our leaders in detention were invited to meet with a team from the government of La Republique du Cameroun on initiating a ceasefire following the United Nation's request to bring an end to the war in Ambazonia," Ayuk Tabe, who is in jail serving a life sentence, said in a statement sent to AFP by his lawyer.
"Once significant progress is made, the interim government of Ambazonia will update Ambazonians," he said, adding that he remains committed to the independence of the two regions.
The nine leaders are self-declared members of the "interim government of Ambazonia". All are in jail in the capital Yaounde, sentenced last August on "terrorism" charges.
The Cameroonian government neither confirmed nor denied the meeting had been held, but a senior UN official told AFP that it took place.
Despite international pressure, it is the first meeting between separatist leaders and the government since the conflict broke out in the two regions, which account for about a fifth of a population that is overwhelmingly French-speaking.
President Paul Biya's government has previously refused to negotiate with the separatist leaders.
It held a "national dialogue" on the conflict in October, but most separatist groups refused to participate, many pointing out their leaders remained in prison.
In early March, the UN called for a ceasefire in the two regions, in part to help combat the coronavirus pandemic.
But the appeal went unheeded, with military operations even seeming to intensify -- the army said it killed 24 separatists in two raids last month.
The sudden softening towards negotiation therefore took many by surprise.
In the statement sent to AFP, the separatist leaders said "no war has ever been wrapped up in the battlefield" and that "real, sustainable peace and independence are a product of the negotiation table".
The statement, which is addressed to separatist militants, said the Thursday meeting was "an initial confidence-building procedure" and that the leaders' position on a negotiated ceasefire was made "clear and unambiguous" to the government.
Cameroon's anglophone protest movement is fragmented into several groups, with the most radical not recognising the "interim government of Ambazonia" and refusing any discussion with the government.
The revelation of the talks -- meant to remain secret, at least at first -- comes as four people were injured by a homemade bomb in the capital Yaounde, which has been mostly spared the violence of the separatist conflict.
- Abuses on both sides -
Both English-speaking regions were once part of British colonies in West Africa called the Southern Cameroons. They joined French-speaking Cameroon after it gained independence from France in 1960.
After months of protests in late 2017, decades of resentment boiled over into an armed campaign for independence that was then met with a brutal government crackdown.
There has been almost constant violence in the two regions since, and more than 700,000 people have been forced to flee their homes.
Rights monitors have said that abuses have been committed by both sides.
The country's armed forces have become mired in a series of high-profile atrocities related to the conflict.
On Thursday, the National Union of Cameroon Journalists condemned the "confiscation" of the body of anglophone TV reporter Samuel Wazizi, who died in custody after being detained in the Southwest Region's capital Buea in August last year.
The army only revealed Wazizi's death last month after international pressure, saying he had worked for the separatists and had died of "severe sepsis".
The union accused the authorities of never releasing Wazizi's body to "hide the bodily harm that the journalist suffered during his incommunicado detention".