The U.K.'s decision to leave the European Union will mean that British companies will be left outside the single market, the EU's top finance minister told CNBC, dashing any U.K. hopes that businesses might still be able to have free access to Europe after Brexit.
"If you choose to leave the EU, you basically choose to be outside the single market," Jeroen Dijsselbloem, president of the Eurogroup, told CNBC on the sidelines of a UBS conference in London.
The leader of the group of 19 euro finance ministers added that once "you are no longer part of the club, you don't get the perks" of its membership.
His comments follow reports that Boris Johnson, the U.K.'s foreign secretary, said that Brexit would likely mean a departure from the EU's customs union - a policy that allows European countries to trade between themselves without tariffs - but would still mean free trade with Europe.
However, according to Dijsselbloem, Brexit means that U.K.-based firms, which currently have full access to the European market, would see some of the benefits of the custom union disappear.
"I don't think he is being realistic and fair to the British electorate on what's possible," Dijsselbloem told CNBC.
The British government has clarified that a decision on the customs union had not yet been taken.
The Dutch finance minister said that the EU has "certainly not seen" any Brexit plan and urged the U.K. government to have a clear strategy before triggering Article 50 next year and officially starting negotiations.
"If there's no plan, no clear choice...that's going to cost even more time," he said, adding that the longer the period of uncertainty the more economic dangerous the situation will get.
Trade and free movement of people are likely to be the hardest points in Brexit negotiations. EU officials claim that the U.K. cannot keep its full access to the single market and restrict the movement of people.
"Everybody now has it in their head that every human being has some fundamental God-given right to move wherever they want. It's not true. That was never the case. That was never a founding principle of the EU. Total myth," Johnson said during a visit to Czech Republic.
Chancellor Angela Merkel of Germany said Tuesday that the EU cannot separate its four freedoms – movement of services, people, capital and goods, to accommodate the U.K.'s goal to restrict immigration. However, she said she was open to discuss the framework of the free movement, the U.K.'s Guardian newspaper reported.
Dijsselbloem told CNBC that there was a lot of disappointment among EU officials on the news that Donald Trump had been elected to be the next U.S. President, but "there's not much point in being disappointed with democracy."
Given the protectionist views of President-elect Trump, Dijsselbloem said he was "not very positive" on a future trade deal between the EU and the U.S. and suggested the focus should be put on the full implementation of the trade agreement with Canada.