Scotland's lord advocate 'disappointed' to learn of the business secretary's desire to have a quick answer on taking action against Fred Goodwin and other RBS directors

Scotland's chief legal officer has rebuked Vince Cable for intervening in Scottish prosecutors' deliberation about whether or not to take action against the directors of Royal Bank of Scotland (RBS) at the time of the taxpayer bailout in 2008.

Lord advocate Frank Mulholland said he was "disappointed" to learn that the business secretary had asked Lord Wallace, advocate general for Scotland, to reach a decision "as quickly as possible" about whether or not to take action against Fred Goodwin and other RBS managers at the time of the bank's collapse.

The matter was referred to Scottish prosecuting authority the Crown Office and Procurator Fiscal Service in January 2012 following a damning report into the bank by the Financial Services Authority (FSA).

Mulholland said the advocate general had no role in the investigation or prosecution of crime, and added that it would be "unfortunate" if Cable's intervention were to be "construed as attempted interference with independent investigation and prosecutorial decision-making by the law officers".

Cable said he was simply asking for an update on the prosecutors' investigation given that it is now five years since the bank's £45bn bailout and "the public are impatient in terms of holding people to account".

He insisted he was "not seeking to influence the outcome". The business secretary is understood to be keen for the Scottish authorities to make a decision so that he can prepare for the possibility of stripping the former RBS bosses of the right to hold company directorships.

Mulholland said the Scottish Crown Office had kept Cable's officials "appropriately advised" of the progress of the "complex and ongoing" investigation. He added that he would be "happy" to brief Cable on the progress of the investigation and the time scale of possible prosecutions if the business secretary contacted him directly rather than via the media.

No one has yet faced criminal prosecution over the collapse of RBS, but a civil case was launched last month by shareholders claiming they were misled by directors over the 2008 £12bn rights issue before the bailout.

• This article was amended on 2 May 2013. The original described Lord Wallace as advocate director for Scotland.