The media was not allowed to attend the trial at the request of Mr Zakhariev's Bulgarian lawyer Hristo Botev.

Mr ???Botev declined the presence of journalists and declined to have a member of the Bulgarian Helsinki Committee, an independent non-governmental organisation for human rights, attend proceedings.

The 21-year-old, also listed as Ivan Zakhariev, is accused of training in the Balkan nation with the intention of fighting in Syria for Islamic State. He denies he attended a shooting range in preparation for combat.

He has been in custody since September, after being detained by the Bulgarian State Agency of National Security and Sofia police.

Mr Botev told reporters waiting outside court that "almost nothing happened today". "We were listening to the records extracted from secret materials," he said.

In September, Mr Zakhariev's father, Svetlomir Zakhariev, told Bulgarian television station BTV his son had been mentally ill since childhood. He defined his arrest as a "gold mine for the country, which wants to demonstrate that it is actively fighting against terrorism".

He said his son converted to Islam and started visiting a mosque when he was 18, after being disappointed with Christianity due to a paedophilia scandal in the Catholic church. However, he later returned to Christianity. Mr Svetlomir Zakhariev has since passed away.

In October, the prosecutor accused John Zakhariev of terrorism. An expert witness testified he was in good psychological health and his intelligence was above average. His lawyers said Mr Zakhariev hadn't prayed for two months before his arrest.

Mr Botev said he expected an expert report to be tabled, and a sentencing statement from the judge to be issued on May 16.

Mr Zakhariev's Australian lawyer Jay Williams declined to comment.

Mr Zakhariev's case is only the third terrorism case in Bulgaria.