Scottish independence: Alex Salmond probed over EU advice row
Independent investigators will look into whether the first minister breached the ministerial code in relation to an ongoing legal row.
Alex Salmond told MSPs he had referred himself to the body.
The SNP leader acted after Labour MEP Catherine Stilher wrote to him asking for a formal investigation.
The issue centres on whether the Scottish government had or had not sought legal advice on the EU status of an independent Scotland.
For more than a year, opposition parties had pressed the Holyrood administration on whether it had commissioned its own law officers to provide advice on the matter.
Both Mr Salmond and his deputy Nicola Sturgeon said they could not reveal that information because they would be in breach of the ministerial code.
The matter went to the courts when Scotland's information commissioner Rosemary Agnew requested Scottish ministers to either confirm or deny if legal advice existed.
The hearing was due to be heard in December. However, on Tuesday, Ms Sturgeon told Holyrood that the government did not have legal advice and planned to commission Lord Advocate Frank Mulholland, Scotland's senior law officer, to now provide it.
The deputy first minister admitted an impression had been given that ministers already had legal advice, but she denied that impression had been formed, in part, by an interview Mr Salmond gave the BBC in March.
When asked by broadcaster Andrew Neil if he had sought advice from government law officers on the question of Scotland's future in Europe, Mr Salmond said: "We have, yes, in terms of the debate."
He added that the advice could be read "in the documents that we have put forward which argue the position that we would be a successor state".
Last year two former lord advocates - Lord Fraser of Carmyllie QC and Dame Elish Angiolini QC - were appointed to the independent panel of advisers on the ministerial code.
But, as the row centres around whether the Scottish government took advice from its law officers on the European question, Mr Salmond announced an extra adviser would be brought in.
Sir David Bell, the vice chancellor of Reading University and a former top civil servant in the UK government's education department, will lead the investigation.
Mr Salmond told MSPs: "The findings of the independent advisers will be made public. I will accept them and I hope all members of this chamber will do the same."
The first minister also pointed out he had been cleared in each of the five previous cases where there had been an investigation into allegations he breached the ministerial codes.
He added: "Each one has found in favour that the ministerial code has been abided by.
"I hope on this sixth occasion, given I have said I will accept the findings, the opposition parties will find themselves able to do the same."
News of the referral came during first minister's questions in which both Labour leader Johann Lamont and Tory leader Ruth Davidson quizzed Mr Salmond on the EU row.
Ms Davidson demanded Mr Mulholland come to the Holyrood chamber to answer questions on the matter.
Meanwhile, Ms Lamont hit out: "Why did the first minister say he had sought advice from the law officers when he had not? Why did he go to court at our expense to stop the release of advice he knew didn't exist?"