Cops have fumed that the Crown Office is “dragging its heels” over the investigation into SNP finances - with Nicola Sturgeonamong the suspects.

Police officers investigating claims of embezzlement of SNP funds are said to have become "frustrated" at the length of the probe.

Operation Branchform was launched over three years ago after complaints were made about how around £600,000 of funds to fight a second independence referendum was spent.

Police Scotland handed a report to the Crown Office two months ago but there has been no further movement on the investigation.

Former SNP chief executive Peter Murrell, who is married to Nicola Sturgeon, has been arrested and charged with embezzlement as part of the probe.

Ms Sturgeon has also been arrested and interviewed by detectives, as has former Nat treasurer Colin Beattie MSP. Neither has been charged but they remain under investigation.

Reports at the weekend suggested officers were probing whether a phantom company received significant cash from the SNP for refurbishment work allegedly carried out at the party's Edinburgh HQ.

Now, Calum Steel, the ex-general secretary of the Scottish Police Federation which represents rank-and-file officers, has spoken out about the time it is taking to bring the probe to a conclusion.

He told The Sun: "The police service will be delighted attention is finally on the as they felt frustrated that the COPFS (Crown Office and Prosecution Service) was trying to drag the inquiry out by asking the police to do more and more. Now only they can answer why the delay."

Operation Branchform has already cost the public purse well over £1 million since it was launched in the summer of 2021.

Scottish Conservative party chairman Craig Hoy said: "This is clearly a long and complex investigation, and that’s why it’s important the police and crown office are as transparent as possible

“It’s understandable that people are asking why this case is taking so long to progress. There may well be good reasons for that but many following it are wanting the authorities to get on with it. As the probe continues the SNP must continue to fully cooperate."

A Police Scotland spokesperson said: "On August 9, 2024, we presented the findings of the investigation so far to the Crown Office and Procurator Fiscal Service and we await their direction on what further action should be taken.”

The Crown Office previously said it had received a 'standard prosecution report' about Mr Murrell’s case.

It referred to its statement from May this year, saying: "Decisions on how to proceed are taken by prosecutors acting independently, and are based upon available evidence, legal principles, and the merits of each case. They are not influenced by political events."

An SNP spokeswoman said: "As this case remains active, it would be inappropriate to comment.”