The Government is ruling out offering some prisoners amnesties to ease pressure on overcrowded prisons.

Chief Justice Dame Sian Elias floated the prospect of prisoners being ordered free, in a speech she admitted would be controversial.

Dame Sian said that the booming prison population had to be managed to prevent overcrowding causing "significant safety and human rights issues".

"Other countries use executive amnesties to send prisoners into the community early to prevent overcrowding.

"Such solutions will not please many ... But the alternatives and the cost of overcrowding need to be weighed."

Justice Minister Simon Power said inmates would not get amnesties.

He also made a pointed remark about the role of the judiciary versus Parliament.

"This is not government policy. The Government was elected to set sentencing policy, judges are appointed to apply it."

Mr Power said the Government would "decide its own policy agenda".

Asked if that could include amnesties, he said: "I have ruled out such a move."

Sensible Sentencing Trust spokesman Garth McVicar said changes outlined in the speech were "totally in the wrong direction".

"If you start holding people accountable, you will get a reduction in crime. Until then I'm afraid we'll just have to build more prisons."

He said he supported the concept of double bunking, and that he had seen tent prisons and container prisons work well overseas in places like Arizona in the US.

However, Howard League for Penal Reform president Peter Williams, QC backed Dame Sian's ideas.

Mr Williams said early release could be granted to prisoners who did not pose a risk to the public or prisoners who were nearing the end of their sentence.

However, he said if it was the former, that could benefit white collar criminals and a public debate would be needed.

"There's absolutely no doubt that there are a large amount of people in our prisons who don't need to be in prison," Mr Williams said.

He said that was detrimental to prisoners and tax payers.

"One can understand an argument that prisoners who are violent and present a danger, may not be on the list, on the other hand, if they are close to being released, they're going to be released anyway."

Mr Williams said there needs to be a coalition between police and social services to stop some problems getting to court in the first place.

He said that would save a lot of money and stop recidivist offenders.

Dame Sian used her speech, made public last night, to signal several changes were needed to be considered in criminal justice.

They included reducing the prison population as well as intervention, community education, probation and improvements in mental health care.

Prison population figures have risen to 8400 and are expected to rise further.