Audit Scotland said the cash would be required over the next two years as the force tries to balance its books.

The reduction of 750 officers was outlined by police chiefs in August last year as one way of breaking even but it would see the size of the force fall to 16,500 officers.

Stephen Boyle of Audit Scotland told the Scottish Parliament’s Justice Committee that a significant cash injection was needed to avoid this outcome.

“Essentially it will be tens of millions of pounds - I would assume in the region of £40-50 million that it would require,” he said.

Scottish Liberal Democrat justice spokesperson Liam McArthur MSP said: “Police Scotland can’t afford to lose more precious expertise. The organisation buckled when it lost around 2000 civilian staff during the SNP’s botched centralisation, and we recently uncovered that it has now lost almost two thirds of its special constables too.

“The national force’s accounts have been in the red since day one, and this continued uncertainty will be extremely unwelcome.

“Lib Dem investigations last year, exposed expert evidence showing that 57 per cent of officers reported that a lack of resources caused them high degrees of stress. Further reductions will only make that worse.

“The Justice Secretary cannot hide from these concerns. He must ensure that Police Scotland has the support and resources it needs going forward to protect our communities. Staff also need to be heard through the staff survey, which is now three years overdue.”