Three ministers have avoided charges after apologising for comments about "weak" terrorism sentencing in Victoria, as the state's appeals court increased the jail terms given to two would-be terrorists.

Key points: Three Coalition MPs avoid charges for comments critical of Victoria's judiciary

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The Victorian Court of Appeal ruled it would not proceed with contempt of court charges against Human Services Minister Alan Tudge, Health Minister Greg Hunt and Assistant Treasurer Michael Sukkar after it heard their apology.

The three men did not appear, but Commonwealth Solicitor-General Stephen Donaghue told the court each apologised "unreservedly" for the comments, published in The Australian newspaper.

"We offer that apology now," Dr Donaghue told the court on behalf of the ministers.

"We never intended to influence the court.

"We intend to exercise great care in the future."

Ministers' behaviour was 'appalling'

The court had previously said the ministers had "failed to respect the doctrine of separation of powers" and "breached the principle of sub judice".

The court welcomed the "full and unqualified apology" but said came after a "stern discussion" between the bench and Solicitor-General, and days of reflection.

"The delay is most regrettable and aggravated the contempt," it said.

The three ministers last week withdrew some of the statements they made, but refused to apologise, when they were called before the Court of Appeal to explain why they should not be charged with contempt of court.

The court said the situation should never had resulted in two court hearings.

"The court states in the strongest terms that it is expected there will be no repetition of this type of appalling behaviour. It was fundamentally wrong," it said.

"It would be a grave matter for the administration of justice if it were to reoccur."

Shadow attorney-general Mark Dreyfus said the ministers were very lucky not to have been referred for prosecution.

"I hope they and other parliamentary colleagues have learned a very serious lesson about their duty as elected representatives to respect the independence of the courts and the need to ensure any comments made are well-informed," he said.

"Prime Minister Malcolm Turnbull now needs to explain why he thought it was a good idea to back in his ministers' comments just after they were made. He should have known better."

DPP wins bid for more jail time

The apology came as two young would-be terrorists at the centre of the ministers' controversial comments had their sentences increased.

Sevdet Besim's sentence was increased from 10 years to 14 years. ( Instagram )

In a separate ruling by the Court of Appeal, the jail term of Sevdet Besim, who plotted to kill a policeman on Anzac Day in 2015, was increased from 10 years to 14 years.

Under that ruling, the 20-year-old will have to serve at least 10-and-a-half years in jail.

In another separate ruling, a 19-year-old known as MHK was sentenced to 11 years in prison, with a non-parole period of eight years and three months, for planning to carry out a bomb attack in April 2015.

He was originally sentenced to seven years in jail with a five-year minimum term.

The original sentences were appealed by the Commonwealth Director of Public Prosecutions (DPP).

'A case of grave criminality'

In the case of Besim, who had planned to run down and behead a police officer at an Anzac Day march, the sentencing judge had taken the man's youth and good rehabilitation prospects into account.

But Court of Appeal Chief Justice Marilyn Warren, Justice Stephen Kaye and Justice Mark Weinberg were critical of that approach.

"What was planned was in effect a most brutal and outrageous crime," a court statement said.

"As this was a case of grave criminality, factors such as rehabilitation and others of a personal nature, including youth, should be given substantially less weight than might be the case in other forms of offending.

"The sentence did not accord with community expectations."

Besim had pleaded guilty to preparing or planning for a terrorist attack — an offence which carries a maximum sentence of life imprisonment.

Penalties should reflect public outrage: court

In the case of MHK, the Court of Appeal found the sentence to be "wholly inadequate" and characterised the respondent's moral culpability as "very grave."

The court found issues with the consideration given to MHK's age and rehabilitation prospects, and said there was not enough emphasis on general deterrence and denunciation.

"Unless appropriate weight is given to those considerations in a case such as this, the criminal justice system will not have sufficiently discharged its duty to properly express the community's outrage at the conduct of the respondent," the court found.

A longer sentence was also necessary "to deter other like-minded individuals from indulging in the same or related conduct".

In a third appeal case, the Commonwealth DPP failed in its bid to increase the sentence for a Melbourne man who admitted sending money to an American to travel to Syria to fight.

Hassan el Sabsabi, 24, was sentenced to 44 days' imprisonment and given a two-year community corrections order for sending a $16,000 payment, but the Court of Appeal rejected the prosecution's argument that the punishment was manifestly inadequate.