Leaked accounts appear to show that the SNP spent more than £670,000 on furnishings, computer equipment and software development last year.
The draft documents, which have been seen by The Sunday Times, raised fresh questions about the party’s finances.
They show that £385,520 was spent on furniture, fixtures and fittings in 2020, as well as £229,750 on computer equipment and more than £55,000 on software development.
The expenditure was higher than the £193,880 spent by the SNP on campaigning, although party sources pointed out that there were no elections in 2020, and campaigning was suspended due to the pandemic.
According to the report, the accounts also showed that donations during the pandemic dropped by 55% from £904,000 to £416,000.
There was little detail regarding staff salaries, which rose from a total of £1,101,000 to £1,259,000.
SNP chief executive Peter Murrell, who is married to First Minister Nicola Sturgeon, reportedly earns a six-figure sum but his salary, and that of other senior SNP officials, has never been disclosed.
One MSP told the newspaper: “HQ operates like a secret society, they need to get out of the bunker, be more open and transparent or stories like this will continue to erode trust in the HQ and its leadership.
“It is clear that there needs to be a clear-out at the top, starting with the chief executive.”
HQ operates like a secret society, they need to get out of the bunker, be more open and transparent or stories like this will continue to erode trust in the HQ and its leadership.”
The details have emerged amid a controversy over £600,000 in donations which were earmarked for a Scottish independence referendum campaign.
Reports in July alleged the party spent vast sums of the ringfenced cash on refurbishing its headquarters, something which has been vehemently denied.
Police are investigating allegations of fraud after the money was raised following an appeal by the party in 2017.
The SNP said: “Despite all the challenges presented by the pandemic, SNP income hit a record high for a non-election year, and we reported a healthy surplus of £1.1 million.
“The party is in great shape as we prepare to secure independence in a post-pandemic referendum.”