YAOUNDE (Reuters) - The trial of three English-speaking protesters facing the death penalty opened at a military court in Cameroon on Monday in a case that has exposed national divisions and stoked opposition to Francophone President Paul Biya.

Since October, people in Cameroon’s two western English-speaking regions have joined protests against what they say is their marginalization by the French-speaking majority under Biya’s 35-year rule.

At least six protesters have been shot dead and hundreds others arrested during the rare challenge to state authority, prompting criticism from human rights groups and concern from the African Union.

The three civil society figures and political activists -- Felix Agbor Balla, Fontem Aforteka’a Neba and Mancho Bibixy -- pleaded not guilty in a court in the capital Yaounde as dozens of security officials stood guard.

They face multiple charges including complicity in hostility against the homeland, secession and civil war, and campaigning for federalism following their involvement in the English regions’ protests.

One of the defendants, Bibixy, made a speech in the regional hub of Bamenda in November while standing inside an open casket meant to show his willingness to die for his beliefs.

“You can see clearly that these are all hyper-political offences which...means you have no chance, none,” said Alice Nkom, a lawyer and president of the Cameroon Anglophone Civil Society Consortium, who is representing Agbor Balla.

In a speech last week, President Biya blamed the unrest on extremist and separatist groups who he said were preaching hate and violence.

“The government had to take measures to maintain order, protect citizens and their property and hand over to the judicial authorities those who committed or were suspected of committing these criminal acts,” he said. “This necessary action will continue.

SURVEILLANCE AND ARRESTS

Cameroon’s linguistic divide dates back to the end of World War One when the League of Nations split the former German colony of Kamerun into zones of French and British administration.

Shortly after independence in 1960, voters from the smaller English zone opted to join Cameroon over neighboring Nigeria - a decision some now regret.

The divisions were in evidence in the courtroom on Monday.

More than a dozen English-speaking defense lawyers wore the elaborate British-style wigs in the French-speaking court, while government lawyers went bare-headed.

The Anglophone lawyers waited patiently for the translation of the proceedings but the quality was so poor that they asked for the interpreter to stop, a Reuters witness said.

The defendants are being tried under a 2014 law created to help combat militants from Nigeria-based Islamist militant group Boko Haram whose fighters regularly launch attacks in Cameroon.

“The anti-terror law is being used to curtail dissent and that infringes on the basic rights and freedoms in the constitution,” Amnesty International’s Ilaria Allegrozzi said.

Cameroon regularly sentences people to death but has not carried out executions for years. The hearing was adjourned and the next one is scheduled for March 23.

Those living in Bamenda, an opposition stronghold, say are victims of a government crackdown since the demonstrations began. The United Nations says the internet has been shut down since Jan. 17 in an apparent bid to quell protests that violates international law.

Residents have responded, shutting down schools and businesses with “ghost town” protests. And some analysts and residents expect further violence if the three men are convicted.

Police officials in the past have said they acted in self-defense against dangerous protesters armed with steel bars and stones.

On Saturday, a national holiday celebrating the referendum that unified Cameroon, the streets of Bamenda were virtually deserted aside from one parade of students bussed in from outside. A surveillance helicopter flew overhead.

“I am telling you we are prisoners within our own homes,” said a Bamenda resident who witnessed the arrest of several of his friends and asked not to be named for fear of reprisals.

“You cannot move freely, you cannot talk with people, you cannot say anything, you cannot just sit with friends and talk.”