David Cameron has come under fresh pressure to toughen Britain's stance on Europe after an ex-minister said he should apply to leave the EU immediately after the general election.

In a speech to the Business for Britain group today, Owen Paterson, the former Environmental Secretary, will urge the Prime Minister to trigger article 50 of the Lisbon Treaty immediately if he wins the election next May.

This would give formal notice of Britain's intention to cut ties with the EU, and "meaningful negotiations" with other nations could then begin ahead of a referendum in 2017, Mr Paterson will say.

According to The Times, Mr Paterson will say the plan would be “enormously attractive to uncommitted voters" who could decide between staying in on the new terms, or leaving with only a trade agreement similar to Norway's.

It would give "our negotiators a very clear mandate”, Paterson will add.

He suggests that voters would opt for staying in the EU because they had not been given a "clear vision of what life outside the EU would look like".

Mr Paterson's comments come as the Tory party decide the best way to respond to the growing poll threat from Ukip, who won the Rochester and Strood by-election last week.

"The eurozone has already embarked upon a path that we can never follow," he will insist.

"We are simply recognising that reality. We must either by fully committed to 'Le Project' or we must build an entirely new relationship.

"The British people must be allowed to make that decision. Article 50 is the only way of making that happen."