Scotland is Now was unveiled in April as part of a bid to set the country apart from its major international competitors.
The £6m campaign is a partnership between the Scottish Government, Scottish Development International, Universities Scotland and VisitScotland.
The branding was created to lure more potential visitors from overseas and the rest of the UK, particularly those in the south-east and London.
But some voters in Scotland have seen adverts for the campaign being promoted on YouTube and noted they contain mentions of several key SNP policies.
The campaign’s homepage prominently highlights the recent completion of the Queensferry Crossing as well as the Baby Box initiative.
Another section of the campaign’s website reads: “Sir Walter Scott’s romantic histories of Scotland in poetry and prose are credited with creating the Scottish tourist industry, and reinvigorating Scottish nationalism and interest in Scottish history.
“It’s possible to argue that he paved the way for the rise of the SNP and the 2014 referendum.”
VisitScotland and Scottish Development International spent almost £500,000 to advertise Scotland Is Now on YouTube in April, including a masthead banner and “in-stream” adverts which play before other videos.
VisitScotland denied that voters in Scotland had been targeted specifically, pointing out many home and work PCs will re-route their IP address via London.
Scottish Conservative chief whip Maurice Golden said: “The SNP is forever blurring the lines between government and party political aims.
“People don’t mind the Scottish Government promoting the country abroad. But they won’t accept the SNP using taxpayers’ money to push their own selfish, separatist message.”
Claire Baker, Scottish Labour’s spokeswoman for culture and tourism, said: “Targeted promotional campaigns like Scotland Is Now, which seek to grow the Scottish tourism industry and promote our country around the world, are always welcome initiatives.
“However, within that process, public money simply must be treated with special care, and there have to be questions asked around the laisse faire attitude taken by those managing this specific campaign.
“At a time when Scotland is basking in glorious summer weather and tourists are seeing our country at its best, there are major concerns around whether or not money available to ensure maximum effect from the Scotland Is Now campaign has been wasted.”
A VisitScotland spokeswoman said: “Scotland is Now is a collaborative campaign to stimulate economic growth and position Scotland as a bold and positive country that is progressive, pioneering and inclusive.
“The UK – in particular, the north east of England and London – remains an incredibly important market and it is essential that we get people from across these areas, to visit, live, work, study, and invest in Scotland.
“The YouTube platform is one of the most efficient ways of engaging with people in that market and as part of the campaign launch for Scotland Is Now planned paid for advertising included promotion on YouTube in the form of a Youtube Masthead.
“This activity, which is only available on a UK wide basis, was live for a period of 24 hours on launch day, delivering impressive results with 85.7million impressions made and a unique reach of 11.4m users achieved.”