MSPs investigating the Scottish Government’s botched sexual misconduct probe into Alex Salmond have expressed “serious concern” about possible missing evidence.

The special Holyrood committee investigating the issue raises the fear in a new letter to the government’s top official, Permanent Secretary Leslie Evans.

The MSPs are particularly worried that Outlook emails and other computer records may have been automatically deleted.

Ms Evans recently admitted: “It is not possible technically to tell what had been automatically deleted or to retrieve material which has already been deleted from the system.”

READ MORE: MSPs warn Nicola Sturgeon about Alex Salmond probe evidence

Earlier this month, the committee agreed to write to Ms Evans about the matter, and this morning released the full text of its three-page letter.

It also released a shorter letter to Nicola Sturgeon asking her to confirm that she would ensure the preservation of evidence held by the SNP as well as by the government.

Ms Evans has already said she will preserve records, while the First Minister has said she will retain emails, files and text messages related to the case.

However the two letters show continued unease among MSPs about the potential for evidence to be destroyed or lost before they have a chance to examine it.

Mr Salmond was the subject of a Government probe last year after being accused of sexual misconduct by two female civil servants relating to his time in office.

He successfully challenged the process in court through a judicial review, showing the lead investigating officer had been in prior contact with both his accusers.

A judicial review ruled that rendered the process unfair, unlawful and “tainted by apparent bias”. Taxpayers have now been left with a £500,000 legal bill.

MSPs are investigating why the probe collapsed and why Ms Sturgeon continued to meet her predecessor while her officials were investigating him in a potential breach of the ministerial code of conduct..

Writing to Ms Evans on behalf of the committee, convener Linda Fabiani said there were “a number of outstanding matters” on which MSPs wanted further information.

She wrote: “The Committee’s main concerns relate to the retrieval of information.

“In particular what it means in practice where you say that ‘It is not possible technically to tell what has been automatically deleted [after 14 months] or to retrieve material which has already been deleted from the system’.

“It appears from this that not only could some information have been deleted, but that it is not possible to establish whether this is the case.

“Given the Committee’s role in scrutinising the Scottish Government’s actions, you will appreciate that this is of serious concern to Committee Members. To address this matter, the Committee would welcome more detail on the Scottish Government’s records management processes, including the technical operation of the system.”

READ MORE: 'Not possible' to tell whether emails relating to Alex Salmond probe have been deleted

Ms Fabiani went on to request a copy of the government’s records management plan, relevant policy documents, retention and disposal schemes, “applying both to Outlook and to any other electronic systems used by the Scottish Government”.

The committee asked for “full copies” of the instructions issued to staff telling them to preserve evidence “rather than just the extracts” Ms Evans previously supplied.

The committee also asked “what efforts have been made to establish whether any relevant information has in fact been deleted either as a result of automatic deletion from Outlook or otherwise” and what efforts had been made to retrieve any deleted material.

The MSPs were also “concerned about the timescales involved” and whether Ms Evans acted quickly enough to preserve evidence after being asked to do so by the committee.

The committee also asked what material had been preserved because it had been needed for Mr Salmond’s judicial review proceedings.

In her parallel letter to Ms Sturgeon, Ms Fabiani said: "Thank you for your reply of 15 April to my letter of 3 April.

"The Committee discussed your response at its meeting on 9 May and agreed that it would expect your commitment to preserve documents and information to apply also to those party members, party staff and other persons employed by

you whose details you committed to preserve in your reply of 15 April.

"Although we assume this will be the case, I would be grateful if you could confirm that this instruction to preserve all documents and information will apply to those individuals."

Mr Salmond is also facing separate criminal charges, including attempted rape.

He strongly denies any criminality.