The First Minister has been accused of abusing his power by spending thousands of pounds in court to avoid answering questions about legal advice that apparently does not exist.
Alex Salmond was branded "a barefaced liar" after his deputy Nicola Sturgeon appeared to contradict his claim that ministers have consulted law officers on Scotland's uncertain future in Europe.
Mr Salmond refused Labour's request to come back to Parliament to clarify the matter further.
The Conservatives have now called on Lord Advocate Frank Mulholland to come to Holyrood to clear up the row.
The Scottish Government and the publicly funded Scottish Information Commissioner have spent £12,000 between them arguing over whether Labour MEP Catherine Stihler had the right to know if legal advice existed on Europe.
The commissioner ruled that disclosure was in the public interest but ministers said confirmation or denial would breach the ministerial code that protects the confidentiality of legal advice in most cases.
Ms Sturgeon's insistence that no legal advice exists effectively brought the legal dispute to an end, but Ms Stihler believes the episode should now be referred Scotland's independent ministerial watchdog.
Mr Salmond told BBC journalist Andrew Neil that ministers had sought advice from Scottish law officers on Europe. During an ad-hoc debate in Holyrood he said he was speaking "in terms of the general debate", insisting that he was not a "barefaced liar" and that his answer is consistent with Ms Sturgeon's statement.
In a letter to Mr Salmond, Ms Stihler said: "Either the statement which your deputy minister gave is incorrect that no specific legal advice existed, or your answer to Andrew Neil is incorrect and your use of the ministerial code to not provide me with the information requested was an abuse of power."
Scottish Conservative leader Ruth Davidson MSP said: "The SNP's twisting and turning in the past 24 hours has made it perfectly clear we can't trust the First Minister to tell the truth, and we can't trust his deputy to come clean either."
