Cheap flights between European locations could be put at risk by the UK leaving the EU, David Cameron has suggested.
The Prime Minister sought to cast doubt on the ability of low-cost airlines such as easyJet and Ryanair to freely operate routes between EU member states after a Brexit.
He made the remarks as he sought to counter arguments from Leave supporters, including London mayor Boris Johnson, that the UK could prosper by emulating Canada's free trade deal.
The PM warned Canadian airlines can operate routes from Canada to Europe but not within Europe.
Mr Cameron also argued there would be struggles for television companies, financial services firms and other businesses in being able to easily access markets in EU countries.
The Prime Minister made the claims as he sought to rejuvenate his campaign for a Remain vote at June's referendum following an Easter holiday in Lanzarote.
Despite pleas from some pro-EU campaigners to offer a positive outlook on Britain's future, Mr Cameron used an appearance in Birmingham to frequently emphasise the dangers and uncertainty of an exit.
His comments came as a poll indicated that Downing Street's tactics, labelled Project Fear by critics, were working, with the Remain camp on 51% and Leave trailing on 44%.
The Orb poll for the Daily Telegraph found that only 5% said they are undecided, with those who currently say they do not know how they will vote more likely to back the Remain campaign on June 23.
When certainty to vote is taken into account, the campaigns are virtually tied, with Remain on 49% and Leave on 48%.
Speaking to PwC workers in Birmingham, Mr Cameron said: "Now, Canada has – or is about to have – the biggest free trade agreement there is with the European Union and some of the principal proponents of Britain leaving the EU have said we should have a Canada-style deal.
"But here's the rub – the Canada-style deal does not have really any good provisions about services.
"Let me just give you a couple of examples – a Canadian airline can fly between Canada and a European city but it can't fly within Europe.
"What does that mean for easyJet or for Ryanair, for companies like that that are so vital in terms of the cheap air flights that we all enjoy?
"Let me give you another example – if you're a television station, if you're located in Britain you can broadcast all the way through the European Union, not if you're a Canadian television station under the deal.
"Think of financial services, and you help so many financial services companies, with our arrangements inside the single market if you're located in Britain you can trade in any European country.
"If you're Canada, your financial services companies won't be able to do that – they have to set up in each and every European country."
The PM added: "If we leave the European Union, and if we have a deal like a Canada free trade deal, it will be very bad for our economy.
"It will be bad for jobs, it will be bad for investment and it will be particularly bad for services industries that need those markets."
Earlier, Mr Cameron also warned leaving the EU would be an "act of economic and political self-harm" and would not help the beleaguered British steel industry.
In reply to the comments made in the Telegraph, Vote Leave's chief executive Matthew Elliott said: "The greatest act of economic self-harm is that we send Brussels £350 million every week in return for handing control of our economy and democracy to EU judges.
"It is deeply regrettable that the PM is basing his campaign on doing down Britain and ignoring the free trade zone from Iceland to Turkey that we will be part of when we vote Leave."