Three Coalition Government ministers are required to appear before the Victorian Court of Appeal on Friday over their comments attacking the state's judiciary for being weak on sentences for terrorism offences.

In the past week, Health Minister Greg Hunt, Human Services Minister Alan Tudge and Assistant to the Treasurer, Michael Sukkar, have all criticised the state's judges in an article in The Australian in relation to appeals in two cases in which the court had reserved its decision.

The Age revealed a letter had been sent to Attorney-General George Brandis requiring the trio to appear before the court and the ABC has seen a copy of the letter.

"The attributed statements were published whilst the judgements of the Court of Appeal were reserved," the letter said.

"The attributed statements appear to intend to bring the court into disrepute, to assert the judges have and will apply an ideologically-based predisposition in deciding the case or cases that the judges will not apply the law.

"The attributed statements, on their face, also appear to be calculated to influence the court in its decision or decisions and to interfere with the due administration of justice in this state."

The ministers or their legal representatives are required to appear before the Court of Appeal on Friday to make submissions about why they should not be referred for prosecution for contempt.

Shorter sentences for terror offences 'deeply concerning'

The comments followed a statement from the Court of Appeal on Friday, that there appeared to be an "extremely worrying" difference between sentences for terror offences in Victoria and New South Wales.

They also came as the Commonwealth Director of Public Prosecutions challenged a 10-year main sentence and seven-and-a-half-year minimum imposed on Anzac Day terrorism plotter Sevdet Besim by Victoria's Supreme Court last year.

One man was killed and three police officers injured during the Brighton siege. ( ABC News: Patrick Rocca )

Mr Hunt told The Australian the Victorian Government should reject "deeply concerning" comments from the court concerning sentences for terror offences.

"Comments by senior members of the Victorian courts endorsing and embracing shorter sentences for terrorism offences are deeply concerning, deeply concerning," he told The Australian.

"The state courts should not be places for ideological experiments in the face of global and local threats from Islamic extremism that has led to such tragic losses."

"No-one should be suggesting that tough terrorism sentences are a bad thing," Mr Tudge told Sky News.

Mr Sukkar joined the criticism in The Australian.

"It's the attitude of judges like these which has eroded any trust that remained in our legal system," he said.

Prime Minister Malcolm Turnbull also roundly criticised the Victorian parole system after a man on parole launched a terror attack at Brighton on June 6.

Comments 'eroded' confidence in the judiciary

Melbourne lawyer Rob Stary earlier told ABC Radio in Melbourne that the comments from the ministers in that context could be seen as having eroded public confidence in the judiciary and amounted to contempt of court.

He filed a formal complaint with the Commonwealth Director of Public Prosecutions, alleging the MPs had "scandalised the court."

He alleged the comments were designed to influence the court in the Besim matter.

"We must have in the separation of powers doctrine an independent judiciary who should be free from political interference," Mr Stary told ABC Radio Melbourne.

"What we say is there has been a contempt of court.

"We say there's been a flagrant breach of that doctrine, particularly from people who should know better."

Mr Stary said the matter should be referred to the Australian Federal Police or some other "appropriate body" for investigation and charges to be laid.

"While it was fine to make a complaint about a sentence or to attack the inadequacy of a sentence, Mr Stary said, it had to be done in "a proper way".

"It's not open slather," he said.

"Judges are independent and they should be free from any political interference."

Mr Hunt, Mr Tudge and Mr Sukkar have been contacted by the ABC for comment.