Dundee-based Labour politician Mercedes Villalba stepped into a row with independence supporters after appearing to make the case for leaving the UK.
The North East regional MSP caused a backlash after asking what was stopping Nicola Sturgeon from taking power companies into public ownership.
The first minister had earlier said nationalisation should be “on the table” for UK-wide firms as energy bills continue to soar ahead of winter.
The SNP claimed Ms Villalba was inadvertently making the case for independence because Holyrood does not have the power to take existing companies out of the private sector.
“Knowing which powers are devolved and which are reserved should be basic for any MSP,” an SNP spokesman said.
“Mercedes Villalba should know fine well that nationalising energy companies is not within the power of the Scottish Parliament.
“She is either being ignorant or wilfully misleading.”
What's stopping her? https://t.co/i8ODJC1hdh
— Mercedes Villalba (@LabourMercedes) August 21, 2022
“However, if Ms. Villalba would like a Scottish Parliament that can nationalise private energy companies, she should get behind Scotland becoming an independent country with the full powers to be able to do that.”
The Labour MSP pointed out the first minister had backed down on a promise made in 2017 to create a new publicly owned firm in Scotland.
She insisted this was “perfectly permissible” under devolution.
Speaking on Monday, Ms Sturgeon blamed the Covid pandemic for her government’s failure to deliver.
She also claimed her state-run energy firm proposal would not have stopped the current energy crisis.
Ms Sturgeon said: “We’d still be facing this energy crisis and the powers to make a meaningful intervention on that would still lie with the UK Government.”
Broken promise
Five years ago, Ms Sturgeon told SNP members: “In our manifesto last year, we also pledged to explore the option of a new publicly owned energy company.
“It would give people, particularly those on low incomes, more choice and the option of a supplier whose only job is to secure the lowest prices for consumers.
“I’m delighted to announce today that by the end of this parliament, we will set up a publicly owned, not-for-profit energy company.”
The first minister indicated she still wants to take forward “modified plans” by creating a new national public energy agency.
Ms Sturgeon warned all future energy price cap rises must be stopped to prevent poorer households from falling into “destitution”.
Labour leader Keir Starmer has also demanded the UK Government suspend any further bill increases.