LEAVING the EU could put £230 on the cost of a family holiday and £4 on the price of a phone call home, David Cameron has claimed, as he set out what he termed the “retail” case for continued membership.

But the PM’s latest salvo in the increasingly bitter referendum battle is likely to intensify allegations of scaremongering from the Leave camp, which strongly disputes the Whitehall calculations over the economic cost of Brexit as negative propaganda.

Speaking at the Luton HQ of low-cost airline easyJet, Mr Cameron drew on analysis by the Treasury suggesting a 12 per cent slump in the value of the pound against the euro if the UK votes to quit the EU in the June 23 referendum.

According to government calculations, by 2018 the weaker pound will mean four people on a nine-night break to Spain could pay £225 more, with eight nights in France up £210, a fortnight in the US £620 and 10 nights in Portugal £325,

Mr Cameron told airline workers: “If we were to leave, and the pound were to fall – which is what most people expect and what the Treasury forecast – that would put up the cost of a typical holiday for a family of four to a European destination by £230.

“It could put up the cost of air travel, because if you are outside the single market – which is what those who want us to leave think – then you would face all sorts of bureaucracy and restrictions that you don’t face today.

“Another very retail thing that is happening in Europe is, we are abolishing roaming charges in the European Union. It’s one of the most annoying things – you’re on holiday, you use your mobile phone, you get an enormous bill. Getting rid of roaming charges could mean on a 10-minute call back to the UK, you’re saving almost £4.

“I think there are some very strong retail arguments about the cost of a holiday, the cost of food, the cost of using your phone, for staying in the European Union.”

Despite stressing the consumer benefits of EU membership, Mr Cameron insisted he was not offering a “head against heart” trade-off, in which the economic case for Remain is pitched against the patriotic appeal of Leave.

Staying in the EU was the “big, bold, patriotic” thing to do, because Britain’s strength and standing in the world were enhanced by its membership of international bodies, he said.

“I think the big, bold, patriotic case is to stay in a reformed European Union to fight for the sort of world that we want, rather than to stand back and be on the outside,” said Mr Cameron.

Mr Cameron’s former policy guru Steve Hilton – who backs Brexit – said the holiday price warning was another example of the sort of “pathetic, patronising EU scares” being deployed by both sides.

“You’ve got to be kidding. It’s almost like a parody,” he told the Press Association.

“I just wish we could have a serious debate about the long-term future of how we want to be governed rather than this kind of nonsense. It just does not do anyone any favours. It just puts people off the whole political class.”

Mr Cameron’s latest offensive came amid a furious response from Eurosceptic Tories to Monday’s Treasury analysis which warned that Brexit would plunge the UK into a year-long recession and cost up to 820,000 jobs.

Vote Leave chief executive Matthew Elliott said: “It’s remarkable to see the Prime Minister talking down our country and our economy day after day.

“Yesterday Nicola Sturgeon pleaded with the Government to stop the negative campaigning, and urged them to stop making exaggerated claims that insult the public’s intelligence. Clearly they’re not listening.

“These threats lack credibility - the pound has actually been stable in recent months as the possibility of Brexit has increased.

"The truth is that leaving the EU will liberate the UK and allow us to do trade deals with countries like India and China - helping our economy to grow.”