The police inquiry into the SNP's spending of £600,000 in party donations cost the tax payer more than £2million.
Operation Branchform probing the party's finances has been underway since mid 2021, still with no decision on potential prosecutions.
It was launched when donations of over £600,000 earmarked for independence campaigning did not appear to be shown in the SNP's accounts.
But now, The Times reports, it has emerged the cost of the investigation itself has dwarfed the sums actually being investigated.
A Freedom of Information request first reported in the Scottish Daily Mail revealed the policing costs of £2,106,961 - which “does not include pension contributions” of officers working on the case.
Early figures showed that the cost of the investigation between 2021 and the beginning of 2024 was around £1.3million, so the cost in just the last year has been around £800,000.