Scotland’s procurator fiscal could launch a probe into Better Together over missing accounts from the independence referendum.
The pro-UK campaign group, which no longer exists after September’s vote, has failed to submit all required information for its invoices, according to the Electoral Commission.
It came as the watchdog published details of the spending by campaigners which shelled out more than £250,000 campaigning on the constitution.
The commission said: “The submitted return of the registered campaigner Better Together is missing some information, making the return incomplete.
“For such matters relating to the Scottish Independence Referendum the commission liaises with the Crown Office and Procurator Fiscal Service (COPFS) in Scotland.
“We are consulting with the COPFS in order for them to consider whether they will open an investigation into this matter. Depending on the response from the COPFS the commission will then consider whether to take any further action itself.”
Forty-two organisations and individuals registered with the commission as campaigners at the referendum. Altogether, they reported spending of £6,664,980.
Five registered campaigners reported spending of more than £250,000 campaigning in the regulated period, to a sum of £5,230,642.
Campaigners spending more than £250,000 were required to submit an independently audited return to the commission by March 18 this year.
Better Together outspent Yes Scotland but, when the supporting political parties were taken into account, SNP cash meant those advocating a separate Scotland ploughed more cash into their campaign.
In one case, the SNP spent £34,720.32 on a helicopter which former First Minister Alex Salmond used to take him between venues.