THE SNP’s “iron discipline” could crack after May’s Holyrood election, with members possibly speaking out against the UK remaining in Europe, a former deputy leader has claimed.

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.

Sillars joined Vote Leave Scottish director and former Labour MP Tom Harris on a visit to Port Glasgow, Inverclyde.

The SNP grandee 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, 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 European Commission president José Manuel Barroso had said it would be “difficult if not impossible” for Scotland to join the EU.

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, lies in democracy.”

Also at the launch, Harris said Brexit could secure the future of free university education in Scotland.