THE UK Government has brushed aside a warning from Britain’s ambassador to the European Union that agreeing a trade deal with the Brussels bloc following Brexit could take as long as 10 years.

Sir Ivan Rogers told ministers in October that other EU members believed a trade deal might not be hammered out until the early to mid-2020s and that EU leaders thought the final Brexit deal was likely to be a free trade arrangement rather than continued single market membership.

Theresa May was asked about the ambassador's warning as the Prime Minister arrived for today's EU summit but she declined to give a direct response.

After former minister Dominic Raab, a leading Brexiter, dismissed Sir Ivan as a “gloomy pessimist,” Mark Garnier, the International Trade minister, told MPs it was "very, very difficult" to work out how long any trade deal would take, pointing to the swift four-month period needed to secure an agreement between America and Jordan and the longer Trans-Pacific Partnership[TPP], which had taken potentially eight years.

He described Sir Ivan’s remarks as "words from interlocutors" rather than a definition of how long it would take to create a UK-EU trade deal.

But Labour called on the Government to give investors the certainty they "desperately need" and outline the UK's hopes for trading arrangements with EU member states.

Bill Esterson, the Shadow International Trade minister, told Mr Garnier: "Today, we are told it could take up to 10 years to reach a trade agreement with the EU after we leave while research from NIESR[the economic think-tank] suggests a drop in trade of up to 60 per cent if we're outside the customs union.

"Foreign investors are vital to the British economy, so will you give those investors some of the certainty they so desperately need and we also need as well?

"Will you tell them whether you want Britain to be inside the customs union and whether you want tariff-free access to the single market or not?"

Mr Garnier replied by insisting the Government was not giving a running commentary on the UK strategy.

"I would also stress that the comments of Ivan Rogers are the opinions, taking words from interlocutors and this is not necessarily defining how long it'll take to create a trade deal.

"It's worth bearing in mind that if you like at some trade deals around the world, whilst TPP has taken potentially eight years, it's worth bearing in mind the US-Jordan trade deal took just four months.

"So it is very, very difficult to be able to establish exactly how long any trade deal will take," he added.

Chris Leslie, a former Shadow Chancellor, warned Britain faced a "mammoth bureaucratic task".

He told Liam Fox, the International Trade Secretary: "Shouldn't we be thanking our ambassador to the European Union for the reality check that he's given about the decade-long period of time it will take for us to extricate ourselves from this particular process? Shouldn't we be not rushing so headlong into this timetable?"

Dr Fox replied: "Yes, there are a number of bureaucratic challenges that we face but the people we should be thanking are the British people for giving us such clear instructions to leave the European Union."

He added: "We have repeatedly set out our worries about the slowdown in the growth of global trade. That has implications across the globe and it's worth making the general point that we need more free trade because it will increase global prosperity."

Meantime, the Secretary of State issued a blunt response to the SNP's Tasmina Ahmed-Sheikh, who said that while the Government's target was to double exports by 2020, the Office for Budget Responsibility expected UK trade to reduce as a result of leaving the EU.

Dr Fox replied: "I'm tempted to ask her if she would like Santa to bring a dictionary, because expectations and targets are not the same thing."