The scandal revolves around the botched police investigation into the takeover of Rangers in 2011, when Sir David Murray sold the club for £1 to Craig Whyte.

A fraud inquiry a year later into the collapse of the club saw a number of men wrongly prosecuted.

Paul Clark and David Whitehouse secured £21m in damages from the Crown Office as well as an apology from then-Lord Advocate, James Wolffe KC.

Charles Green, who became the chief executive of Rangers, won an out-of-court settlement of £6.4m after being maliciously prosecuted.

It was reported earlier this year that Mr Whyte was seeking £10 million from Police Scotland.

Asked at Holyrood how much the scandal had cost so far, Interim Crown Agent John Logue said said: “As of [Tuesday], the stage at which the litigation has now reached the point where the costs have increased to just under £51m.”

He was also asked if further expenditure was expected or being agreed to.

Mr Logue said: “There’s always a degree of speculation about such matter, and I recognise that, but I am afraid the general position remains as it was explained to you before by the Lord Advocate that you’ll understand there is still ongoing litigation.

“Therefore that limits what I can say, but obviously the litigation has reached the stage where I’m not publicly able to confirm it.”

Scottish Liberal Democrat justice spokesperson Liam McArthur MSP said: “This is a truly vast sum of money for the government to have thrown away.

“The Scottish government are threatening major cuts to policing and court budgets. That’s where this money should have been spent.

“We need to see progress on a full, independent and judge led inquiry into this scandal.”