One of Bulgaria's leading human rights advocates says his support for Australian Jock Palfreeman has prompted a government push to deregister his organisation.

Key points: The Bulgaria Helsinki Committee provided support to Jock Palfreeman while he was inside prison

The Bulgaria Helsinki Committee provided support to Jock Palfreeman while he was inside prison Since Palfreeman's release from jail on September 20, the BHC has come under attack from government figures

Since Palfreeman's release from jail on September 20, the BHC has come under attack from government figures Palfreeman is locked up in a detention centre while he awaits deportation from Bulgaria

The far-right Bulgarian party VRMO, one of two parties sharing power in government, has written to the prosecutor general demanding that the Bulgaria Helsinki Committee (BHC) be banned.

In a press release, the VRMO claimed that by organising seminars with prosecutors and judges and by representing clients in the European Court of Human Rights and before domestic courts, the BHC was interfering with judicial independence.

Krassmir Kanev, chairman of the BHC, described the move as "part of a wider battle between reformists and the old guard".

"This is an unprecedented attempt to silence a human rights organisation in Europe," Dr Kanev said.

"Even in [Vladimir] Putin's Russia, [such] organisations were branded as 'foreign agents' but none was prohibited."

One of BHC's clients is Palfreeman, 32, who was convicted of murder and attempted murder in 2009 and sentenced to 20 years with a non-parole period of 10 years.

"I think that my support to Jock's case played a role in this," Dr Kanev said.

Jock Palfreeman is in a detention centre awaiting deportation after being released from jail. ( Supplied: Dobrin Kashavelov )

The Australian has always claimed he was acting in self-defence during the 2007 street fight in which he stabbed and killed local law student Andrei Monov.

Palfreeman established Bulgaria's first convicted prisoners' union while he was in prison. With Dr Kanev's help, he has taken the cases of other prisoners to European and Bulgarian courts.

Palfreeman was granted parole on September 19 and released from prison the next day but was taken to a detention centre for illegal migrants because he did not have a passport.

Although he now has the requisite paperwork and has agreed to deportation, Palfreeman is still locked up in the detention centre while a political storm rages outside.

The Supreme Judicial Council, which oversees the judiciary, sided with public and political condemnation of the three judges who granted parole and their judgement.

A far-right party known as Ataka has protested outside the Bulgarian courts against Mr Palfreeman's release. ( Dobrin Kashavelov )

Almost 300 judges have returned fire with a strongly worded letter decrying the loss of judicial independence that this represents.

Last week another far-right party called Ataka protested outside the Sofia Palace of Justice. Some of the signs read "Helsinki Committee — prosecution under Article 105 for espionage in favour of a foreign state".

Dr Kanev said the timing of the VRMO attack is designed to further a wider political agenda by playing off the furore over the Palfreeman case.

"The entire proposal was made in the framework of that debate. And it is supposed to put further pressure on the Palfreeman case, although this is by no means its only and probably not its major purpose. The latter is the attack on the reformist judges," he said.

"We treat the VMRO attack as coming from the Government. The VMRO is part of the governing coalition; their president is Deputy Prime Minister."