Alex Salmond is taking the Scottish Government to court following complaints about his conduct during his time as first minister.
Mr Salmond said he had been denied the chance to properly challenge the complaints, which he denies.
The allegations relate to his behaviour towards a member of staff at his official Bute House residence in 2013, the Daily Record reported.
In a statement, Mr Salmond said: “The Permanent Secretary chose to deny me contact with any current civil servant, many of whom wished to give evidence on my behalf and access to documentation to allow me to properly challenge the complaints, all of which I refute and some of which were patently ridiculous.
“The procedure as put into operation by the Permanent Secretary is grossly unfair and therefore inevitably will lead to prejudicial outcomes.
“It is therefore with great reluctance that I have today launched a Judicial Review in the Court of Session which will decide the issue of the lawfulness of the procedure which has been used against me.”
Mr Salmond could not be contacted for comment on the nature of the complaints against him.
A Scottish Government spokeswoman said: “For legal reasons we are currently unable to comment.”