More than £2bn worth of UK exports to Canada could be in jeopardy after Brexit, Theresa May has been warned as she flies to Ottawa for her first official meeting with Canadian Prime Minister Justin Trudeau.

According to Open Britain, the organisation campaigning for a soft Brexit, the controversial EU-Canada trade deal – known as the Comprehensive Economic and Trade Agreement (Ceta) – is expected to boost British exports to Canada when it comes into force next week.

But the organisation notes that Ceta will cease to apply to the UK in March 2019 when Britain formally leaves the bloc. It means the deal, which was hammered out in negotiations spanning seven years, will have to be renegotiated by the UK with the Canadian PM.

In 2013 the UK Government estimated that the deal would increase UK exports to Canada by 29 per cent. Open Britain adds this would boost UK exports by £2.117bn.

Chris Leslie, a Labour MP and supporter of Open Britain, told The Independent that the Prime Minister is “on thin ice” as she begins her visit in the Canadian capital.

He added: “The best the Prime Minister can even hope for is that we ‘copy and paste’ the deals the EU has negotiated on our behalf. That is what Theresa May will be begging Justin Trudeau for when she arrives on her visit today.

“But doing so will be harder because of her plans for a hard, extreme Brexit. The worse our access to the EU market becomes, the less likely it is that we will get a good deal from the Canadians.

“To preserve our trade, both with Europe and with economies around the world like Canada, Theresa May needs to rethink her ideological choice to leave the single market and the customs union.”

Ms May is anticipating, however, that an agreement will be reached with Mr Trudeau to swiftly form a new bilateral agreement between the UK and Canada after Brexit.

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Ahead of the visit, Downing Street said: “They are expected to agree the establishment of a new joint working group to prepare the ground for transitioning the deal.

“They are expected to agree the establishment of a new joint working group to prepare the ground for transitioning the deal”

Speaking ahead of the visit the Prime Minister added: “My visit to Canada today is not only about recognising our past but also looking ahead to our bright future. We are both countries with ambitions to lead on the world stage and progressive values that underpin those ambitions – values including the importance of free trade, and respect for international law.

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“When we come together and work as one to project our shared values on the world stage, we form a powerful union.”

Responding to the Prime Minister’s official visit to the Canadian capital, the Liberal Democrat Brexit spokesperson Tom Brake said Ms May was “racking up air miles trying to recreate what we already have”.

He continued: “This copy-and-paste Brexit is a huge waste of time and resources. Can ministers point to a single country that has responded to their plea for new and improved trade deals?