Yaound - Three members of Cameroon's English-speaking opposition, which protests that the country's linguistic minority is being treated as second-class citizens, pleaded not guilty to terrorism charges at a military court on Monday.Felix Agbor Nkongho, an attorney, Neba Fontem Aforteka'a, a teacher, and Mancho Bibixy, also called "BBC", a radio host, were arrested in January and charged with conspiracy to commit "acts of terrorism, secession, revolution, insurrection" and "inciting civil war".All charges are punishable by death. More than 160 lawyers have lined up in support of the defendants.The trial was originally scheduled to begin on February 1.After preliminary proceedings, in which the three declared they were not guilty, the case was postponed once more on Monday until March 23 to allow the state to present its list of witnesses."We haven't yet completed our investigations," the prosecutor said. "We are still registering victims."The trial affects "freedom of thought and freedom of belief," said Charles Tchoungang, a defence attorney. "Are we now going to rush to gag freedom of speech?"Defence lawyers also complained that the prosecution was flouting the law by failing to hand over their witness list five days before the start of the trial.A fifth of Cameroon's 22 million people is anglophone -- a legacy of the unification in 1961 of two colonial-era entities previously run by France and Britain.Anglophones have long complained that Cameroon's wealth has not been shared out fairly and that they suffer discrimination.The majority francophone country is headed by President Paul Biya, 83, who has been in power since 1982.Secessionists are calling for the establishment of an independent state called Southern Cameroons. Bibixy is accused of being a leading secessionist figure in Bamenda, the epicentre of the revolt.Nkongho and Fontem are prominent members of the Cameroon Anglophone Civil Society Consortium (CACSC), a now-outlawed organisation that backs secession.In January, the group called for protests in the country's two English-speaking regions, longtime opposition bastions, bringing several cities to a standstill -- a so-called "ghost town operation."The government responded by cutting off the internet in those regions.