No-one involved in the £46billion collapse of Royal Bank of Scotland will face prosecution despite a five-year inquiry into potential criminality, the Crown Office has announced.

The taxpayer was forced to bail out RBS - which had been led by controverisal chief executive Fred Goodwin - at the height of the financial crisis in 2008.

The Lord Advocate ordered an investigation into banking irregularities in Scotland in late 2011.

A Crown Office spokesman said that there had been a "thorough, independent investigation".

He added that it had "involved detailed consideration of whether there was any evidence of criminal conduct."

“This was an extremely complex investigation which included the examination of over 160,000 documents by a team of specialist forensic accountants and banking experts, supervised by the Serious and Organised Crime Division.

“The investigation involved close co-operation with a range of financial regulators and banking institutions, including the Financial Conduct Authority, the Prudential Regulation Authority, the Federal Reserve Bank of New York, the Serious Fraud Office and the Financial Reporting Council.

“Following careful examination of all the evidence seen to date, Crown Counsel have decided that there is insufficient evidence in law of criminal conduct either in relation to RBS as an institution or any directors or other senior management involved in the rights issue.

“If any further evidence comes to light which is relevant to this enquiry it will be considered by the Crown and we reserve the right to make further enquiry, if considered appropriate.”

Last year the perceived delay in the inquiry was questioned by Ian Fraser, the author of Shredded: Inside RBS, The Bank That Broke Britain.

The RBS bail out came after a period of expansion within the bank.

Mr Goodwin, its former chief executive, was stripped of his knighthood.