Yes Scotland called in police to probe allegations that email accounts belonging to the campaign were illegally accessed.
Blair Jenkins, the Yes Scotland chief executive, had claimed the attack, which allegedly took place three months ago, was “a serious assault on democracy” and had been disruptive to the campaign.
In a statement, Detective Superintendent Steven Wilson said: “Police Scotland has investigated a complaint regarding unauthorised access to a private email account where communications with Yes Scotland were illegally accessed.
“Inquiries to date have revealed no indication the access of this material was the primary motive of the culprit. Yes Scotland has assisted Police Scotland at every stage of the inquiry, which continues in relation to the offence committed against the private individual.”
A spokesman for Yes Scotland said that the inquiry was still continuing into the “illegal hacking of a personal email account of a senior member of the Yes Scotland team.”
He added: “This account was being used for Yes Scotland business and there is no dispute the information being unlawfully accessed from it related directly to Yes Scotland.”
Better Together, the pro-Union campaign, accused Yes Scotland of wasting police time.
A spokesman for the campaign told The Herald: “Under serious pressure over the damaging allegations contained in the leaked emails, the First Minister implied media involvement in hacking the email accounts of the independence campaign and threatened serious repercussions for the media. Blair Jenkins then claimed they ahd been subject of a sinister criminal attack.”
He went on: “The reality is this was a deliberate and cynical attempt to deflect attention away from the fact the Yes campaign had been caught deceiving Scots. This has been an extraordinary waste of police time.”
The claims emerged after revelations that the Yes campaign had paid Dr Elliot Bulmer following the publication of an article in The Herald.