Liam Fox will today suggest voters are being bullied to stay in the European Union by false claims an Out vote could break up the UK.

The Conservative former defence secretary will also accuse the Remain camp, which includes David Cameron, of being in a “unholy alliance” with the SNP on the issue.

Earlier this week the Prime Minister became the latest senior figure to suggest leaving the EU could increase the chances of Scottish independence.

Dr Fox's comments come less than a day after the Business Secretary Sajid Javid appeared to criticise the Mr Cameron, saying that he had hoped for more from his EU renegotiations.

But the French came to the Tory leader's aid suggesting that camps holding thousands of migrants could close in Calais and relocate in the UK if it left the EU.

In his speech, Dr Fox will accuse Mr Cameron of taking the “equivalent of a political begging bowl" around other EU states "to secure minor changes”.

And he will argue that voters in Scotland are not as pro-EU as the SNP has suggested.

A recent survey suggested that 60 per cent of Scots are eurosceptic, just five per cent below the UK level.

The Tory MP will make an emotional appeal to those who feel "they are being bullied into making a decision on the British membership of the EU because of threats made by the SNP to break up the UK."

It “doesn’t follow” that a leave vote would trigger another independence referendum, he will say, accusing the SNP of “sabre rattling” on the issue.

A second vote can only be legally called with Westminster’s backing.

And staying in the EU will not persuade the SNP to give up plans for another independence poll, he will say.

“It is therefore a perfectly possible that English eurosceptics who voted to remain in the EU because of their worries about the integrity of the Union could find themselves with the worst of both worlds – locked into ever closer union in the EU with the Union imperilled anyway."

The SNP would also struggle to win another vote against the backdrop of a low oil price and the continued problems in the eurozone, he will add.

Meanwhile, Nicola Sturgeon has said that the vast majority of SNP members want to campaign for a remain vote.

Her comments came after Jim Sillars, the party's former deputy leader, urged supporters to shrug off their "blind loyalty" to the SNP and vote to leave on June 23.

Ms Sturgeon's chief political spokesman dismissed the calls, saying: "Jim is Jim."

Elsewhere, French President Francois Hollande hinted that France could suspend the agreement that allows British border police to operate in Calais if there was a 'Brexit'.

France was accused of “blackmail” over the claims, by David Davis, the Conservative MP and a spokesman for the Grassroots Out (GO) campaign.

Tory London mayor Boris Johnson also accused Mr Cameron of scaremongering about the risks of leaving the EU, and of “clutching the skirts of Brussels”.

But there was a split on the benefits of EU membership among the business community.

The Society of Motor Manufacturers and Traders backed a vote to remain in Europe.

But the bosses of more than 200 small businesses said in a joint letter that Britain should leave the EU.

The Chancellor George Osborne warned that leaving would be a “costly divorce”.

But his ally Mr Javid appeared to gaffe saying "I wish there was more in the deal" that Mr Cameron secured from Brussels.

The pro-EU Universities Minister Jo Johnson was also forced to defend his brother Boris's decision to campaign against the Prime Minister and denied he had "stabbed" Mr Cameron in the back "because of his own ambition".

"On the contrary," he said, "it's a free vote as set out, the collective responsibility has been suspended for the duration of the campaign.

"People have sincerely held views on both sides of this question. What's really important is that we have a civilised, well-informed debate that's up to the challenge and up to the magnitude of the decision we will all be taking."