Aust told Bulgaria about NSW man: lawyer

The Australian government told Bulgarian authorities a Sydney man who's in jail in the Balkan state was "interested in terrorism", his lawyer says.

John Zakhariev is in a Bulgarian jail facing allegations he trained in that country with the intention of fighting in Syria for Islamic State.

His lawyer, Hristo Botev, has told the ABC the Australian government notified Bulgarian authorities in a letter that Zakhariev had been in Syria in 2013 and "he is interested in terrorism".

"This is what came from Australia, nothing more," Mr Botev said.

In a statement the Australian Federal Police said: "The AFP does not confirm or deny who it may or may not be investigating, nor does it comment on matters of intelligence."

Comment has been sought from the department of foreign affairs.

Local media reported last year investigations into Zacharia began when national security agencies became aware of his "activities".

It's alleged there was evidence the 21-year-old had been in contact with terrorists and radical Islamic preachers online.

His father, who died in February, told local TV in 2016 that Zachariev had a mild form of autism.

He said his son converted to Islam after becoming "disappointed" in pedophile Catholic priests but later returned to Christianity.