Professor John Curtice said there remained “question marks about whether or not the party could be trusted with donations”.

The SNP may be losing out on donations due to the impact of a long-running police investigation into party finances, the country’s top pollster has warned.

Professor John Curtice said there remained “question marks about whether or not the party could be trusted with donations that are coming in”.

More than £2.3m has been spent by police and prosecutors on Operation Branchform so far, with 10 detectives still assigned to the case.

John Swinney’s party remains ahead of Scottish Labour in all recent polls with the First Minister credited for steadying the Nationalists’ ship after a turbulent 18-month period following the resignation of Nicola Sturgeon in February 2023.

A survey of voting intentions out yesterday predicted the SNP could be on course to return 55 MSPs at next year’s crunch Holyrood election.

But the spectre of Operation Branchform continues to hang heavy over the party with no end in sight to the investigation launched back in July 2021.

Detectives are investigating how more than £600,000 of donations to the SNP for the purpose of fighting a second independence referendum were ultimately spent.

“Operation Branchform is a problem for the SNP, insofar as it does make it more difficult for them to raise money,” Curtice told Sky News.

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“Because there are question marks about whether or not the party could be trusted with donations that are coming in that being spent for the appropriate purpose.

“And the party, at the end of the day, will want to be able to fight the Holyrood election with as much financial heft and resource as it can possibly muster.”

The Strathclyde University academic continued: “A lack of financial resource may well make it somewhat more difficult for the party to run an effective ground war.

“It may not be able to spend so much money on advertising or on social media. Maybe that could cost it one or two seats, and as I have explained, because the prospect of there being a pro-independence majority at the moment looks as though it is literally on a knife edge that could matter.”

Sky also reported policing costs had soared to at least £2,106,961. The Crown Office, which is Scotland’s prosecution service, said in its FOI response that it had spent at least £206,366.

Swinney yesterday refused to comment about a selection row involving Colin Beattie, an SNP MSP who remains under investigation as part of Branchform.

The former party treasurer aims to stand again as a candidate at next year’s Holyrood election.

Asked if Beattie would be an asset or a liability to his party, Swinney told reporters yesterday: “I’m not going to talk about any issues that have any proximity to a police investigation.”

Beattie’s arrest in 2023 came two weeks after Peter Murrell, the former SNP chief executive, was initially arrested.

A house belonging to Murrell and Nicola Sturgeon was also searched by officers for two days.

Murrell, the former SNP chief executive, was rearrested and charged in connection with the embezzlement of funds from the SNP in April last year.

No decision has yet been announced on whether he will face trial.

A SNP spokeswoman said: “As we approach the election, recent polling shows strong levels of support for the SNP under John Swinney’s leadership, as we deliver the progress people in Scotland deserve on the issues that matter to them.”

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