Nigeria’s decision to conduct the trials of suspects charged with terrorism behind closed doors has been criticized by human rights advocates.

The West African nation last week began implementing a new court practice that bans the media and the public from trials involving terrorism charges at the start of the trial of a pro-Biafra separatist leader.

Nnamdi Kanu, who holds dual Nigerian and British citizenship, leads the Indigenous People of Biafra campaigning for the secession from Nigeria of the Igbo, Nigeria’s third-largest ethnic group.

Kanu’s trial in the capital, Abuja, resumed behind closed doors a day after the nation’s Federal High Court announced that court proceedings for offences of terrorism “shall be held in camera,” prompting concern among many human rights advocates.

“We are concerned that this breaches the constitution,” Anietie Ewang, Nigeria Researcher in the Africa division of Human Rights Watch told The Associated Press of the secret court trials.

If Nigerian authorities fear that confidential security information could be made public in a terrorism trial, those concerns should be examined “on a case-by-case basis,” Ewang said, “as opposed to giving out a blanket ban that would clearly restrict public scrutiny.”

Kanu is accused of leading terrorism-related activities and instigating violence in Nigeria’s southeast, including a jailbreak in Imo state last year that led to the escape of nearly 2,000 inmates. He denies the seven charges including terrorism and felony. Eight other charges were dropped by the court when the trial resumed last week.

The proceedings against Kanu “should be a public trial that the whole world can watch,” his lawyer Mike Ozekhome said, likening the secret court sitting to “a gathering of witches and wizards in a coven.”

The concerns are not just about Kanu’s trial, say the activists as Nigeria has dozens of terrorism suspects in detention, many who have been held for years.

“The right to a public hearing safeguards the fairness and independence of the judicial process and helps to maintain public confidence in the judicial system,” Amnesty International Nigeria office told The Associated Press.

Except when a secret trial is meant to protect the interest of a child, “court hearings and judgements must be public,” said Seun Bakare, head of programs at Amnesty Nigeria.