Jim Sillars said he did not believe there would be “unanimity” among the party’s MPs, MSPs and MEPs on the issue.
He also said he could “not understand” why the SNP is campaigning for the UK to remain in the European Union (EU) and that leader Nicola Sturgeon had been wrong to make a pro-EU speech in London.
The former SNP MP spoke out at the launch of the Vote Leave campaign in Scotland – though he stressed he is not a member of that organisation.
Mr Sillars joined Vote Leave Scottish director and former Labour MP Tom Harris on a visit to Port Glasgow, Inverclyde.
The veteran nationalist said he wanted the UK to leave the EU because this could make it easier for Scotland to become independent.
While the focus is currently on the Scottish Parliament vote on May 5, Mr Sillars said: “I am hopeful that after the election the iron discipline of the SNP will start to dissolve.
“Maybe after the election where this iron discipline has got be maintained, we’ll get some people telling us what they really believe.
“I want Brexit for entirely different reasons from any other group campaigning at the moment, because I believe it will enable Scotland to become independent much easier than if we remain inside the United Kingdom inside the European Union.”
In the run-up to the 2014 independence referendum, then then European Commission president Jose Manuel Barroso had said it would be “difficult if not impossible” for Scotland to join EU
Mr Sillars said: “I personally do not understand why my colleagues in the SNP are arguing for the UK to remain inside the European Union.
“On the EU itself my fundamental objection, as well as having being told by them to get stuffed on independence, my fundamental objection lies in democracy.”
He argued there is an “unelected central organisation” in the EU, saying: “When you had 12 member states and the veto was in operation for all member states over a large area of policy then the centre was constrained, when you have 28 members it strengthens the centre.
“That is why we have got unelected people in the commission – nobody elected the guy who is in now, nobody elected Barroso before him. It’s an elite and a self selecting elite.”
Mr Sillars added: “My objection to the SNP policy is that if we remain in the United Kingdom, which remains inside the European Union, then the next time we have a referendum on independence we will have the European Union on the Better Together side saying ‘you can’t get in, you can’t get in’, and therefore sowing uncertainty and fear.”
Mr Sillars also said that “as soon as Nicola Sturgeon went south of the border to campaign for remaining in” she had legitimised David Cameron’s position that the June 23 vote is a “whole UK referendum” .
The SNP leader has repeatedly warned that a second independence referendum could be triggered if Scotland votes to stay in Europe, but the UK as a whole votes to leave.
But Mr Sillars said:”She might have had more traction in her argument if she had stayed north of the border. As soon as you go south of the border and campaign there than you accept it’s an all UK one.”