Earlier this month, opposition MSPs of every party backed a Scottish Conservative motion calling on the government to release the legal advice they received for Alex Salmond’s legal challenge.

Former SNP minister Alex Neil abstained in that vote and said afterwards: “The government is going to have to release this legal advice. In my view the founding principles of the Parliament are openness, transparency and accountability. In this instance, the logic of that is this legal advice has to be given to the committee.”

SNP MSP Linda Fabiani, the Salmond inquiry committee convener, has also criticised the government repeatedly for not co-operating and refusing to release key documents.

However, the government have still refused to hand over the legal advice they received for the judicial review about their investigation of sexual misconduct claims against Mr Salmond.

Scottish Conservative leader Douglas Ross said: “I have instructed the party to start preparations for launching legal action if the government refuses to listen to the Scottish Parliament and release these key documents.

“They have already ignored one vote in the Scottish Parliament. If they ignore a second vote this week, the Scottish Conservatives as the lead opposition party will seek to deliver what MSPs across the Scottish Parliament have demanded.

“The committee is being obstructed and blocked from doing its job. The First Minister’s promises to “co-operate fully” have been broken.

“If the government continues to abuse its power to shut down scrutiny, the Scottish Conservatives will look to force their hand so we can find out how more than £500,000 of taxpayers’ money was lost.”