Over 500 inmates are set to be released from prison under emergency legislation from the end of June if new regulations are approved by MSPs.

Justice Secretary Angela Constance has published the regulations, which estimate around 550 eligible prisoners will be released in four tranches next month.

There were 8,313 people in Scotland’s jails on Wednesday – down slightly from the 8,348 prisoners when Ms Constance announced the plans two weeks ago.

At the time, she warned there had been an unprecedented increase of around 400 inmates since March 18, leaving the prison estate at “critical risk”.

The Early Release of Prisoners and Prescribed Victim Supporters Regulations are set to be put to MSPs within two weeks and are expected to come into force on June 13.

If approved, people serving sentences of less than four years who are due to be released within six months will be eligible for release under Section 11 of the Bail and Release from Custody (Scotland) Act.

However, the Scottish Conservatives have already confirmed they will not back the emergency regulations over public safety fears.

Prisoners serving life sentences and those convicted of terror-related, sexual or domestic violence will not be eligible.

Prison governors will also have a veto to prevent the release of an eligible prisoner whom they consider to be an “immediate risk” to a group or individual.

Ms Constance said releases will take place in “tranches” to “safely resettle” the prisoners involved.

She said: “Emergency early release has become necessary to ensure the safety and wellbeing of Scottish Prison Service staff and those in their care as a result of the rapid rise in the prison population, creating an unprecedented situation.

“This rise of around 400 prisoners over the last two months is significant and could not have been anticipated, and it cannot be ignored, it is also similar to challenges faced across the UK.

“Protecting the public remains my number one priority, which is why there are significant and robust safeguards in place.

“I recognise concerns victims may have, which is why named victim support organisations will be given information about the release date of a prisoner under the emergency release process, where requested by the victim they are supporting to enable a more trauma-informed approach.

“This is part of a significant package of measures we are taking in both the short and long term to deal with rising prisoner numbers, and I will continue to engage with Parliament, victims organisations, local authorities and other key partners as we progress these proposals.”

But Tory justice spokesman Russell Findlay said: “In a matter of days, the SNP Government has increased the number of prisoners it wants to release early by 10%.

“Sneaking this out while all attention is on their expenses-fiddling MSP is shabby, even by their standards.

“The public deserve to know the full extent of how many criminals are going to be set free, when this will happen and what measures are being taken to protect the public.”