Trade commissioner Cecilia Malmstrom also insisted the UK must leave all the EU economic pacts it currently participates in as a member when it quits the bloc. 

However, she left open the possibility that Britain will be able to remain part of the club’s web of trade deals during a two-year transition period to soften the blow. 

The Swedish official made the remarks during an interview at an EU Trade Policy Day event in Brussels just hours after a proposed divorce deal with Britain spectacularly collapsed. 

EU and UK negotiators had an outline exit agreement drawn up yesterday and were all set to publish it before the DUP erupted over a special clause relating to the Irish border. 

The unionists sunk the deal over wording that committee Britain to maintaining “regulatory alignment” between the North and South of the island of Ireland after Brexit. 

They feared this would give Northern Ireland a special status and threaten the break up of the UK, with SNP chief Nicola Sturgeon immediately calling for her own special deal. 

The pact would have meant EU leaders were able to sign off on sufficient progress at next week’s crunch summit, meaning trade talks could have begun as early as March. 

Now that declaration hangs by a threat, and Ms Malmstrom said she and her team will only begin drawing up plans for a future free trade agreement once they have been given “a green light” by EU capitals. 

She said: “Now we will have a member who will leave us and then leave the internal market and thereby not having the advantages that you have in the internal market.

“It will be a third country and with a third country if we have no trade agreement there will be the WTO most favoured nation rules, but we are aiming to have a trade agreement of course. 

“How long will it take, what will be the content, how ambitious will it be? That is too early to say. But it cannot be 100 per cent total frictionless trade because they are not in the internal market.” 

Ms Malmstrom said there are still “thousands of things to solve in the divorce process” meaning that talks between the two sides on issues like citizens’ rights will continue well into next year. 

And the Swedish commissioner was uncompromising when asked if Britain can continue to benefit from the around 50 trade deals the EU has signed with countries across the globe after Brexit. 

She said: “No, I don’t think so frankly. That is frankly their problem. When they leave the EU they also leave the trade agreements that they have been part of and how they want to deal with this, well.

“I don’t think that is possible, no. They leave the EU. Unless they are part of the Customs Union, but if they leave the EU they have to leave these trade agreements, that’s nothing new. 

“There has been talk of a transition period - that is something that will be decided. But the other trade agreements with the third countries, with Canada, with South Korea and others they will have to leave.”