21-year-old Australia John Zahariev was arrested for extremist preaching in Bulgaria. Picture: Supplied

The dual Bulgarian Australian citizen was taken into custody on September 20 last year after being charged with allegedly training as a terrorist with the intention of travelling to Syria to fight for Islamic State.

He denies the charges.

At a hearing in the Special Criminal Court in the capital Sofia, Judge Vrancheva closed the court to journalists, citing the planned presentation of specialist surveillance evidence.

The case was adjourned on Friday night, with Mr Zahariev’s Bulgarian lawyer Hristo Botev saying he expected a sentence to be handed down on May 16.

The apparent sentence is scheduled despite no formal declaration of Mr Zahariev’s guilt or innocence being made public.

Bulgaria laid the charges after they received a notification from the Australian Government alleging Mr Zahariev had an interest in terrorism.

The precise charges against Mr Zahariev have not been made public but they relate to allegations that he was teaching himself to shoot on instructions from jihadists.

RELATED: Former Sydney schoolboy held in Bulgaria on terror charges

RELATED: Australian John ‘Ivan’ Zahariev’s terror trial delayed

21-year-old Australia John Zahariev was arrested for extremist preaching in Bulgaria. Picture: SuppliedSource:Supplied

Bulgaria does not have juries and he is appearing before a single judge.

He was also supported by Sydney barrister Jay Williams, who was in court for the hour-long appearance.

Mr Williams has previously represented asylum seekers detained on Manus Island.

Mr Botev had earlier said Mr Zahariev returned to Bulgaria last year to help his father, Svetlomir Zahariev, settle into retirement.

Mr Zahariev, who was aged in his 80s, had been supporting his son through the court appearances, but died earlier this year.

His mother, a Vietnamese-Australian woman, is based in Australia and is undergoing treatment for cancer. She visited him in March and was able to spend time with him at the Sofia Central Prison.

Mr Zahariev attended Waverley College in Sydney’s eastern suburbs but appears to have converted to Islam afterwards.

His lawyer has said he went to Syria on humanitarian work in 2013 but left after a week after discovering it was “cruel’’ on both sides, and the propaganda was wrong.

He has also said his client has converted back to Christianity in August last year.

The dual Bulgarian Australian citizen was taken into custody on September 20 last year. Picture: SuppliedSource:Supplied

Police have bugged his conversations with his father, and interviewed people at a shooting range he visited in Bulgaria.

Mr Zahariev is being held in the same jail — the Bulgarian Central Prison — as another Australian man, Jock Palfreeman, who is serving a 20-year sentence after being convicted of murdering a man in a street fight in Sofia.

Chairman of human rights group the Bulgarian Helsinki Committee, Krassimir Kanev, worked with Mr Zahariev’s father and said his father believed his son had been set up.

Mr Kanev told News Corp he had been unable to access any of the documentation relating to the case.

“I need to see the documents. I am afraid that the first documents I see will be the sentence.’’

Mr Kanev said Bulgaria had a very high rate of convictions in court — more than 90 per cent of all defendants either pleaded guilty or were found guilty.

He said a person found innocent was able to make a claim against the government over their imprisonment.

Dilyana Angelova, from the Helsinki Committee, has been attending the case as an observer, and said she had assisted Mr Zahariev’s mother visit her son in prison in March.