The Scottish Government intends to bring forward legislation to quash convictions of victims of the Post Office scandal before the summer.

At a meeting of the cabinet on Tuesday, the justice secretary Angela Constance said the UK government is "inexplicably" refusing to extend legislation for sub-postmasters in Scotland, despite doing so to Northern Ireland.

Humza Yousaf, however, has said he still has hopes the legislation will cover all four nations and will ask the Prime Minister to reverse the decision not to extend the legislation.

Calling the decision "unacceptable and outrageous", the first minister said he was "utterly furious" that the proposed law will cover every other part of the UK. However, a Westminster insider said the position being taken by the SNP was "nonsensical", saying it was "hypocrisy" that the SNP government is asking for interference in what is a devolved matter.

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UK Enterprise minister Kevin Hollinrake, in a letter to Ms Constance, said that it was more appropriate for Holyrood to legislate, given Scotland's distinct legal system.

Previously, the Scottish Government has argued that the fastest way to secure parity for Scotland's estimated 100 victims of the faulty Horizon IT system is to have blanket legislation across the UK.

Hundreds of sub-postmasters were accused of embezzlement, theft and other crimes due to the Horizon system.

In England, the Post Office prosecuted cases privately while in Scotland the Crown Office and Procurator Fiscal Service has sole responsibility for prosecutions.

The new UK bill will give people who were wrongly convicted the chance to settle their cases for financial redress of £600,000.

It is understood by The Herald that Scottish ministers want to be confident their bill will be compatible with the UK wide compensation scheme before it becomes law.

Ms Constance said: “We fully support the extension of this Bill to cover Northern Ireland, but it is outrageous that the UK government has declined to also include Scotland.

“Sub-postmasters north of the border will be the only victims in the UK not covered by the legislation at Westminster."

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Speaking to the broadcaster LBC on Tuesday afternoon Humza Yousaf said: "I am utterly furious by the fact that the UK Government have chosen to extend their legislation to every single part of the United Kingdom except Scotland.

"The unfair treatment of Scottish sub-postmasters and sub-postmistresses is completely unacceptable.

"We've got a letter from the UK Government saying they are going to extend the scope of the bill to Northern Ireland but not to Scotland.

"That is outrageous and the fact of the matter is that it's hard to think that the UK Government are doing anything other than using our sub-postmasters and mistresses as a political pawn.

"That's unacceptable, it's outrageous and I'll be writing to the Prime Minister in order to ask him to reverse that decision."

The Scottish Government will bring forward its own legislation to exonerate sub-postmasters who were wrongly convicted because of faulty software.

Northern Ireland Secretary Chris Heaton-Harris said that the "legislation will deliver for those affected in NI as quickly as possible".

Mr Hollinrake said the UK Government was extending the remit of the legislation, because the "significant and unique challenges" the recently restored administration there would face in bringing forward legislation at an "expedited pace".

The Post Office minister told Ms Constance that without action from Westminster there was a "risk of significant delay to justice for postmasters in Northern Ireland", adding this would result in a "lack of parity with others affected across the UK".

He confirmed: "We have therefore concluded that the Bill should be amended to quash convictions in Northern Ireland in light of these unique circumstances."

However he said Scotland was an "historically separate legal jurisdiction", noting prosecutions had not been carried out by the Post Office, but by the Lord Advocate, the most senior prosecutor north of the border.

As a result, Mr Hollinrake made clear: "It remains the UK Government's view that it is more appropriate for the Scottish Government to bring forward proposals to address prosecutions on this matter in Scotland, and for these to be scrutinised by the Scottish Parliament."

While the minister insisted the UK Government would "continue to support" the Scottish Government in developing its own legislation, his letter prompted an angry response from Ms Constance.

She said: "We fully support the extension of this Bill to cover Northern Ireland, but it is outrageous that the UK Government has declined to also include Scotland."

The Justice Secretary added: "This ignoring of Scotland is typical of Westminster's attitude.

"It means that sub-postmasters north of the border will be the only victims in the UK not covered by the legislation at Westminster, which is precisely where the miscarriage of justice has its origins and was overseen by successive Tory and Labour governments.

"It is a betrayal of Scotland's Horizon victims for UK ministers to behave in this manner."

Ms Constance told how sub-postmasters had suffered "one of the biggest miscarriages of justice in UK legal history", adding that those affected in Scotland "do not deserve to be subject to Westminster's petty political point-scoring.".

Noting that amendments have been laid in the Commons which could extend the UK Government's Bill to Scotland, she added: "We still hope that MPs overrule the UK Government and amend the legislation so that it covers Scotland.

"But if that does not happen, Scottish legislation will be introduced."

A UK Government spokesperson said: "Justice is a devolved matter in Scotland so it is right that Scottish ministers remain accountable for decisions taken in Scotland.

"The Scottish government has already indicated that they are bringing forward legislation, and we will continue to support them in developing proposals to overturn all convictions relating to the Horizon scandal in Scotland."