Ivan Roger's resignation left Westminster stunned and sparked allegations of chaos | Thierry Roge/EU via EPA UK ‘screwed’ in Brexit negotiations, says ex-ambassador The UK and EU could end up in a ‘trade war,’ Ivan Rogers tells MPs.

LONDON — The U.K. has been “screwed” in Brexit negotiations because it triggered Article 50 too soon, the country’s former EU ambassador said.

Ivan Rogers, who resigned as the U.K.’s permanent representative to the EU in January, also warned that a “bloody” no-deal scenario could be set in motion as early as December, and could end up with the two sides in a “trade war” and wanting to "knock chunks out of each other."

Giving evidence to MPs on the House of Commons treasury committee on Wednesday, Rogers said he advised Prime Minister Theresa May last fall not to invoke Article 50 “unless you know how Article 50 is going to work” but was opposed by “various people in London.”

In an excoriating critique of May’s Brexit strategy, he said: “My advice as European negotiator was that this was the moment of key leverage and that if you wanted to avoid being screwed in negotiations in terms of the sequencing, if I can put it brutally, you had to negotiate with the key European leaders and the key people at the top of the institutions and say ‘I will invoke Article 50 but only under circumstances where I know exactly how it’s going to operate and it’s got to operate like this otherwise this is not going work for me.'”

However, May’s decision to invoke Article 50 at the end of March gave the EU the opportunity to “set up the rules of the game in the way that most suits them,” Rogers said. EU negotiators were aware the U.K. wanted the talks to progress to trade at the earliest opportunity and used this as leverage to demand more money as part of the divorce settlement, he said.

He said the more pressing the need to talk about trade and transitional arrangements becomes for the U.K. and for the British private sector, "the more likely they are to be more generous with their money."

“Anybody could have told you that that’s exactly what the 27 would do,” he added.

Rogers, who warned of “muddled thinking” in government in his resignation email to staff at the U.K. Representation to the EU (known as UKRep), said he has not changed his view that getting a trade deal with the EU could take until the early to mid-2020s.

He also warned that despite the EU agreeing at last week’s European Council to begin internal preparations for transition and future relationship talks, the bloc's proposals at a summit in December could include “difficult, uncomfortable elements” that might derail the negotiations.

He predicted that the EU would seek more concessions on the divorce bill before it agreed to a transition deal, potentially demanding “another £30 billion” to cover the U.K.’s commitments — above and beyond the roughly £20 billion pledged by May as part of the EU’s current budget plan to 2020.

He said there was a risk May would reject such a proposal.

“I think at that point, if there’s a breakdown at December Council or at an emergency January or February Council, both sides will be thinking 'is this the end of the negotiations? Do we have to go somewhere else?’”

Such a breakdown of talks would be “unlikely to be anything other than bloody,” Rogers said, prompting the EU27 to begin contingency planning for a breakdown of legal agreements with the U.K. on issues such as aviation, financial services and data protection.

“If it’s getting really conflictual and bad, trust levels will be very low, there will be a huge amount of name-calling across the Channel, there will be a big fist fight, and the U.K. will be saying 'we’ll make our own contingency plan,'” he said.

“There is not a guarantee the two sides will come together in some affable moment at the end of 2018 … It may be so bloody by then that both sides are looking to knock chunks out of each other and start a trade war, who knows?”