Theresa May is set to meet the EU's chief Brexit negotiator in London amid fresh splits over the transition period after Britain leaves the bloc.
The Prime Minister will see Michel Barnier when he attends a working lunch with David Davis on Monday ahead of the next phase of talks - in a rare example of the divorce discussions taking place outside of Brussels.
It comes as Ms May faced increasing pressure to set out her position on the UK's long term relationship with the European Union in the face of growing dissatisfaction from both wings of the Conservative Party.
Mr Davis posted on Twitter: "Looking forward to welcoming Michel Barnier to London on Monday. Important next step in our work to build new partnership between UK and EU."
Downing Street confirmed that Ms May would also meet Mr Barnier on the trip, which comes as officials were due to begin the next phase of Brexit talks, where the UK is expected to give an update on its plans for the future relationship.
Tensions over Brexit have ramped up in recent days after leaked Whitehall analysis suggested that Britain would be worse off on leaving the EU under all possible scenarios.
Ms May appeared to relent to pressure from Tory right-wingers by saying she would not guarantee the rights of EU citizens who arrive in Britain during the transition period, which is one of the key EU demands.
The comments provoked anger from Brussels, while the European Parliament's Brexit chief Guy Verhofstadt said the rights of EU citizens up to the end of the transition in 2021 were "non-negotiable".
The Prime Minister also resisted pleas to clear up confusion about her aims for the long-term relationship with the EU – despite warnings that her dithering would trigger a vote of no confidence in her leadership from Tory backbenchers.
Speaking to the BBC on a three-day visit to China, she refused to accept the choice between maintaining close economic ties with Brussels or making a clean break.
"These are not the options that we have before us,” she said and maintained it was possible to “negotiate a good trade deal” and also “take back control” of money, borders and laws.
Asked which was more important, she replied: “I don’t believe that those are alternatives".
In sign of the fraught atmosphere in Westminster, Brexit minister Steve Baker was also forced to apologise for airing a conspiracy theory that civil servants were distorting evidence in favour of a soft Brexit.
Ms May said he had not broken the ministerial code because he would “amend the record that has given to Parliament and apologise to Parliament".
The row centred on leaked Whitehall analysis, obtained by Buzzfeed News, which set out a range of potential scenarios, where even if the UK was able to negotiate a comprehensive free trade agreement, estimated growth would be down 5 per cent over the next 15 years.
That would rise to 8 per cent if Britain left without a deal and was forced to fall back on World Trade Organisation (WTO) rules.
Asked about the upcoming Brexit talks, a Downing Street spokesman said: "My understanding of what the EU has set out is that these talks on the future relationship will be at a technical level looking at the process and structure of how the talks on the future relationship proceed."
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