Australian Jock Palfreeman has been released into house arrest in Bulgaria as his fight for freedom took a step forward.

The 32-year-old was released from the Busmantsi Immigration Detention Centre shortly after 3am this morning Australian time.

Bulgarian authorities took his passport, which was only issued in September, to prevent him from leaving the country.

It comes as Dr Simon Palfreeman said from Newcastle said it was "good news" but he was still in the dark about the full details of his son's release.

"It is good news, I'm only just coming to grips with it," he said.

"All I can say is for weeks the prosecutor-general's office and the justice department has been saying that Jock can leave when he has a passport but now his passport has been confiscated."

Palfreeman, a former student at Sydney's elite The King's School, has spent more than 11 years in jail for the stabbing murder of Andrei Monov in 2007.

However, the Australian said outside the detention centre that he wanted to stay in Bulgaria.

"If I had a choice, I would stay in Bulgaria. For those 12 years, it was only Bulgarians that helped me," he said. "Australians became interested in me only recently.

"I will have to go back to Australia after the Bulgarian authorities allow me to do that as I have to sort out some documents," he said.

Palfreeman added in Bulgarian: "If they reopen the case, each judge will feel forced to abandon the case because he can never be impartial after so much media fuss and eventually they will have to find a judge from another country to rule on the case."

"There are many people who have been granted parole and released from jail before and after me and during this trial," he said according to a translation of his comments.

A court ordered he be released on parole last month but the decision has been challenged in Bulgaria's highest court.

A decision on the prosecutor's appeal against the decision was due within two months.

Nikola Nikolov, head of Bulgaria's Migration Directorate, gave a press briefing in front of Busmantsi Detention Centre last night.

Mr Nikolov said Palfreeman's ID document has been confiscated as a guarantee because he has a ban to leave Bulgaria.

Foreign Minister Marise Payne said after Jock Palfreeman's release: "I welcome the release of Jock Palfreeman from Busmantsi Detention Centre, Bulgaria on 15 October.

"I am concerned, however, that Mr Palfreeman continues to be denied the right to return to Australia, having being granted parole in September.

"We call on the Bulgarian Government to ensure Mr Palfreeman receives due process, consistent with Bulgarian law.

"Australia has provided and will continue to provide everything required to assist Mr Palfreeman's departure from Bulgaria as soon as possible."