The SNP secretly planned to introduce a new tax on Scottish businesses in 2022-23 according to new documents revealed in response to a Freedom of Information request by the Scottish Conservatives.
A Scottish Government policy document outlined proposals to introduce a new tax on energy businesses and potentially increase non-domestic rates.
The Scottish Conservatives said John Swinney must rule out ever introducing the "North East tax" at the SNP manifesto launch on Wednesday.
They also said the SNP must come clean about the scale of their tax-raising plans, since the document is heavily redacted.
Amidst the many hidden sections, the policy paper outlines a "new action" to explore ways to use "tax powers" to target company profits. It goes on to state that "non-domestic rates could be increased..." through a new law.
Scottish Conservative candidate for West Aberdeenshire and Kincardine, Andrew Bowie, said: "These new documents reveal the SNP were secretly planning a huge tax hike on Scottish businesses.
"The SNP's North East tax would have put jobs at risk and hammered the local energy sector.
"John Swinney must rule out ever introducing such a damaging new tax.
"He must also come clean about the scale of these plans because SNP secrecy has limited how much we know about this worrying proposal.
"There are so many redactions that we don't know if the nationalists were planning to try and raise millions or billions from businesses.
"People in the North East deserve to hear straight answers from the SNP. Will they try to introduce this North East tax after the election?
"On July 4th, vote Scottish Conservative to protect tens of thousands of jobs in the oil and gas industry."