The pro-independence Scottish National Party's (SNP) move to ally with British Prime Minister David Cameron in rallying voters to stay in the European Union (EU) is coming under fire from an influential Scottish politician.

Earlier this month, Nicola Sturgeon, First Minister of Scotland and SNP leader, warned a British exit from the EU would place Edinburgh at the "mercy of the most right-wing Tory government in modern history."

If the leave camp prevails at Thursday's vote, speculation is high that Cameron will resign and be succeeded by one of the right-wing figures behind the campaign, such as former London mayor Boris Johnson. Should that happen, Sturgeon said a number of rights, such as maternity leave or vacation leave, could be dismantled.

But such arguments are deceptive and amount to scare-mongering, former SNP deputy leader Jim Sillars told CNBC on Wednesday.

"Whoever forms a Tory administration after Thursday only has a majority of 12 in the House of Commons. No government with a 12 majority will ever start to try to undo the various benefits we have in British law in terms of maternity pay, paternal leave and the right to holidays."

The SNP has also warned that a Brexit could hit Scottish trade with the rest of Europe

"At the moment we are part of a free market where we have access to 500 million other consumers...If we voluntarily withdraw from that free market, we will no longer have access to trading with that free market," SNP politician Joanna Cherry said this week, according to the BBC.

Sillars, a Leave supporter, also shut down that logic.

"There's no reason to believe that if the U.K. comes out of the EU, there will be any problems in trading."

In the case of a 'leave' vote, politicians will begin talks with business and trade unions, who will push for free access with Europe, Sillars explained. "So, a free trade agreement (FTA) is likely to be negotiated between the U.K and EU."

Sturgeon has also cautioned that a Brexit could lead to a second Scottish independence vote but Sillars said that was near impossible.

"She's powerless to extract to the legal right from Westminster so she's deceiving the Scottish people by warning that a second referendum could happen."

The power to grant a referendum lies with the government in London but because Sturgeon failed to get a majority in parliament last month, the SNP no longer possess the majority and mandate to hold a referendum like last time, he explained.

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