SNP MP Kenny MacAskill has asked if the police are to speak to David Davis over claims he made in the Commons last night suggesting "a criminal conspiracy" against Alex Salmond.

Davis, the former Brexit secretary, used parliamentary privilege to make public material he said was handed to him by “an anonymous whistleblower”.

He said the information given to him included a download of text messages from the telephone of Sue Ruddick, the chief operating officer of the SNP, and was held by the police.

Davis said the messages appeared to support the former First Minister's allegation of a concerted effort by senior SNP figures to encourage complaints to the police against him, including by Peter Murrell, Nicola Sturgeon’s husband and chief executive of the party.

Following on from Davis's intervention last night, MacAskill, the MP for East Lothian and a former Scottish Justice Secretary, wrote on Twitter today: “So are Crown Office going to instruct Police Scotland to interview David Davis MP regarding leaked documents? Perhaps the Crown Agent can advise.”

READ MORE: Nicola Sturgeon rejects David Davis's 'conspiracy' claims during Covid briefing

Salmond had previously urged a Holyrood inquiry to seek text and WhatsApp messages between Ruddick and civil servants, ministers and special advisers and other material relevant to its work from his own lawyers.

He said in written and oral evidence to MSPs last month that the messages showed "malicious and concerted efforts" to remove him from public life and even to send him to jail.

The committee has received messages relating to the matter, but they were not published, as MSPs said it wouldn’t be in the public interest to publish the private communications, which they said “were safe spaces for confidential support”, rather evidence of a conspiracy.

But Davis told MPs last night his whistleblower suggested the evidence “points to collusion, perjury, up to criminal conspiracy”.

He told the Commons: “No single sequence of text is going to provide conclusive proof of what the whistleblower described as a criminal conspiracy, but it does show a very strong prima facie case which demands further serious investigation, by which I mean, at the very least, a thorough review of all emails and other electronic records of the relevant personnel at all the relevant times.”

One of the messages, Davis said, showed SNP compliance officer Ian McCann expressing “great disappointment to Ruddick, that someone who had promised to deliver five complainants to him by the end of that week had come up empty or 'overreached' he as he put it”.

The Tory MP added: “One of the complainants said to Ruddick she was feeling pressurised by the whole thing rather than supported. The day following the Scottish Government's collapse of the judicial review in January 2019, Ruddick expressed to McCann the hope that one of the complaints will be sick enough to get back in the 'game again'.

"Later that month she confirmed to [SNP chief executive Peter] Murrell that the complainant was now quote 'up for the fight and keen to see him go to jail'. Ruddick herself expressed nervousness about what happens ‘when my name comes out as fishing for others to come forward’.

Davis added: “Note again, this was after the criminal investigation into Salmond had commenced. This is improper to say the least. Contact with, and influence of, potential witnesses is totally inappropriate once a criminal investigation is underway.

"That was known inside the SNP itself. Text messages revealed that at an SNP National Executive Committee meeting early in January 2019 The Honourable Member for Edinburgh South West [Joanna Cherry] raised concerns amongst staff at Westminster, that SNP headquarters are engaged in 'suborning of witnesses', whilst on the 28th of August 2018, a senior member of SNP staff in this building, described in an email the SNP headquarters move against Salmond as a witch hunt.”

Salmond told the inquiry last month that he believed the motive for the alleged attempts to remove him from public life and send him to jail was to divert attention away from a court ruling that found the Scottish Government's handling of complaints against him was unlawful.

But he said these attempts failed when he was acquitted of all charges at his High Court trial last year.

During his speech, Davis called for further devolution of powers to the Scottish Parliament and said Holyrood had faced “great difficulties exposing what went on”.

The cross-party inquiry had, he claimed, “come up against endless impediments in its efforts to fulfil its remit”.

The Tory MP said: “These difficulties can be traced back to the Scotland Act 1998, in which the British government of the day, and this House, decided to devolve power to Scottish Parliament, but failed to do it properly.

“These failures are broadly on three fronts: first this House failed to guarantee separation of powers to Scotland. We have known for centuries that separation of powers is fundamental to a functioning democracy.

"Yet in Scotland the Lord Advocate both leads the prosecution service, and serves in the Scottish cabinet. This leaves him conflicted and compromised with the department's independence undermined.

"Second, the Scottish civil service was left as a part of the wider UK civil service, and therefore does not have its own mechanisms of control and accountability in place, but it is only loosely controlled by Whitehall.

“The result has been tolerance of failings, which ordinarily would have led to resignations.

“Third, and most important Scottish parliamentarians are not given the same powers and privileges that members of this house enjoy. This means evidence relevant to the Holyrood inquiry, can be freely discussed here, today using parliamentary privilege. But if an MSP in Holyrood were to do the same, they'd like to find themselves facing down prosecution.

“Indeed, the Crown Office has been making such threats to Mr Salmond's lawyers, to various journalists and even the Holyrood inquiry itself. They made clear that they would deem disclosure of evidence to a committee of elected representatives to be a criminal offence.

“We have, in effect, given the Holyrood inquiry, the right to summon evidence, but not to use it. It is because of these failings I brought this debate today.

“We need to reinforce the ability of the Scottish Parliament to hold its own government to account. I am here to strengthen the Scottish Parliament not to bury it.”

In January 2019, the Scottish Government conceded its investigation of Salmond had been unlawful and tainted by bias. It was forced to pay the former First Minister £512,000 in costs.

Davis also alleged that there are messages which suggest Sturgeon’s chief of staff, Liz Lloyd, had been “interfering” in the Scottish Government's complaints process in February 2018.

The First Minister told parliament she first learned to the investigation at her home in Glasgow on April 2, 2018. However it later emerged Salmond's former chief of staff Geoff Aberdein made her aware of them in a meeting in Holyrood on March 29, 2018. Sturgeon has said she forget that meeting as it was a busy day at Holyrood.

Davis said the Crown Office was barring publication of evidence which was "critical in determining whether Nicola Sturgeon breached the ministerial code" relating to when she first heard of the investigation into her predecessor and former mentor.

He said: “It is clearly in the public interest to see this evidence. I have it on good authority that there exists from 6 February, 2018, an exchange of messages between civil servants Judith McKinnon and Barbara Allison suggesting that the First Minister’s chief of staff is interfering in the complaints process against Alex Salmond. The investigating officer complained, ‘Liz interference v. bad’.

“I assume that that means very bad. If true, this suggests that the chief of staff had knowledge of the Salmond case in February, not in April.

“The First Minister tied herself to that April date in both parliamentary and legal statements. She was, of course, aware earlier than that. The question is just how aware and how much earlier.”

The First Minister has repeatedly denied there was a conspiracy against Samond.

Last night her spokesman said: "As with Mr Salmond's previous claims and cherry picking of messages, the reality is very different to the picture being presented.

"Every message involving SNP staff has been seen by the committee previously. Their views have been widely reported as dismissive of them."

Asked about the claims at the Scottish Government's coronavirus briefing today, the First Minister said: "I refute - strongly refute – the suggestions and insinuations from David Davis in the House of Commons last night.

"I am not going to have this Covid briefing sidetracked by the latest instalment of Alex Salmond's conspiracy theory, and that's just how it is today.

"I have given eight hours of evidence to the parliamentary committee looking into this.

"They are now able to assess all of the evidence they've taken, including, I'm sure, the evidence they have in relation to the suggestions and claims made by David Davis last night.

"They have a job of work to do now. I'm going to allow them to do that job of work and in the meantime I'm going to get on with my job, which for the moment is leading this Covid briefing.

"Because I'm pretty sure most of the people watching right now want to hear about the Covid situation. I'll make that comment and that is all I am saying in the course of this briefing."

The National has approached the Crown Office for a comment.