Alister Jack has been accused of a “clear breach” of the ministerial code over a new £150m “enhanced investment zone” which will cover a significant section of his constituency.

The Secretary of State for Scotland revealed that he had used his position as a minister to lobby for Stranraer and Cairnryan to be part of the low tax, low regulation area, when giving evidence to the UK Covid Inquiry on Thursday.

The ministerial code makes clear that ministers “must keep separate their roles as minister and constituency member."

The SNP has called for an urgent investigation, but a UK Government source accused the party of playing politics.

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Details of the new investment zone were announced in the UK Government's Safeguarding the Union command paper published on Wednesday, which set out a number of new initiatives to convince Northern Irish unionists to return to Stormont.

The new £150m zone will cover all of Northern Ireland and, according to the command paper, “will also pursue and engage through the East-West Council on the scope to extend Investment Zone benefits to the Stranraer/Cairnryan area in Scotland - recognising this vital Union connectivity route and boosting growth".

The two ports are the main entry for Northern Irish goods entering Great Britain.

Mr Jack told the Dumfries News that the agreement "not only secures a welcome resumption of the full democratic process at Stormont, it enhances prospects of additional investment in Wigtownshire and for vital improvements to the A75."

The Herald:

During his appearance before the Covid Inquiry, Mr Jack was asked about how salient details of conversations were recorded in the corporate record of the UK Government.

He said: “When I conduct business, I inform my office.

"So, for instance, in the last ten days I have had conversations with the Secretary of State for Northern Ireland directly about including Stranraer and Cairnryan in an investment zone for Northern Ireland, as we move towards Stormont hopefully being up and running again.”

He continued: “And I had a conversation with Jeffrey Donaldson and I then come back to speak to my office directly and inform them that I'm trying to have Stranraer and Cairnryan included in an investment zone for Northern Ireland - because it's not possible to do a free port structure - and they then take that information and go back, officials to officials, whether it's in the [Department for Levelling Up, Housing and Communities] or the Northern Ireland Office, in this case - both DLUHC and Northern Ireland - so investment zones are DLUHC, in Northern Ireland Office - obviously regarding the negotiations.

"They then go back and cement what I, what we, what I think we have agreed."

The Herald:

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Mr Jack was also praised for his work in securing the inclusion shortly after the command paper was published, with a UK Government source telling press: “This will be a huge jobs and investment boost for southwest Scotland. Alister Jack has been the driver behind this exciting proposal which will strengthen Scotland’s economic ties with Northern Ireland and benefit the whole United Kingdom.”

Section 1.3 (h) of the ministerial code states: "Ministers in the House of Commons must keep separate their roles as Minister and constituency Member."

Section 6.4 goes on to say that “where Ministers have to take decisions within their departments which might have an impact on their own constituencies, they must take particular care to avoid any possible conflict of interest.”

It also calls on ministers to “advise their Permanent Secretary… of the interest and responsibilities should be arranged to avoid any conflict of interest.”

SNP MSP Kevin Stewart said: “Alistair Jack’s own words betray the complete contempt and disregard with which the Tories hold the Scottish people. This appears to be a clear breach of the Ministerial code and must urgently be investigated.

“Whether they’re handing out contracts worth millions of pounds for defunct PPE to their pals or stuffing the House of Lords full of their cronies and donors, their rank hypocrisy is clear for all to see.

“Only by voting SNP can we rid Scotland of this corrupt Tory party once and for all, and ensure that we have MPs standing up for Scotland’s values at Westminster.”

Steve Goodrich, Head of Research and Investigations at Transparency International UK, told The Herald on Sunday: “The PM’s code of conduct for his ministers states clearly that they should all take care to avoid conflicts of interests between their roles in government and in parliament.

“While those in government may lobby colleagues about constituency issues, they need to be clear which hat they’re wearing when doing so, and seek advice from civil servants before stumbling into potentially inappropriate behaviour.”

A UK Government spokesperson said: “Alister Jack was acting in his capacity as Secretary of State for Scotland.

"The NI / Stranraer Investment Zone will be a huge boost to jobs and the economy of south west Scotland. It will strengthen Scotland’s economic ties with NI and benefit the whole UK."

A UK Government source added: ‘The SNP have repeatedly failed the south west of Scotland.

"They should welcome this huge boost to the area but, true to form, all they can do is play politics."

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 Speaking at First Minister’s Questions in Holyrood on Thursday, Humza Yousaf said there had been no meaningful consultation with the Scottish Government on the plans and they had not seen the proposals before they were published this week.

“It would be fair to say we weren’t given any advanced sight of the command paper that was published by the UK Government yesterday, there was no meaningful engagement by the Westminster Government,” he said.

“The UK Government appears to have unilaterally decided that there will be no border control post at Cairnryan – it’s not a decision that they have consulted us on.”

Mr Jack's Dumfries and Galloway seat is a marginal with the minister beating the SNP by just 1,805 votes in 2019. He has announced that he is standing down at the next election.

A recent MRP YouGov poll suggested the constituency would be one of just two gains for the SNP at the next election.