Theresa May will travel to Brussels on Wednesday for Brexit talks with European Commission president Jean-Claude Juncker.
Downing Street said the meeting was part of the “ongoing negotiations over the future framework” agreement with the EU.
It is understood the talks are set to focus on future long-term relations between the UK and EU, rather than on the withdrawal deal that Mrs May unveiled last week.
The move follows a stormy few days for Mrs May, which have seen the DUP deliver a warning shot across Government bows after accusing the Prime Minister of breaking fundamental promises on Brexit.
And a number of Tory MPs are still pushing for a vote of confidence in the PM, although their attempts to topple her appear to have stalled.
Justice Secretary David Gauke said a move to oust Mrs May would be “dangerous for the country”.
He told BBC Breakfast: “The idea that at this point, in the middle of a very delicate negotiation, that is hugely important to the future of this country, that we should remove the Prime Minister, essentially leave us leaderless, for certainly several weeks, possibly months, would be hugely irresponsible.
“I don’t think people should be talking about removing her at this point.
“I think that would be self-indulgent and dangerous for the country.”
In another cause for concern for the PM, Mrs May’s Spanish counterpart Pedro Sanchez has said Madrid will vote against the withdrawal deal at a special EU summit on Sunday if Gibraltar’s future is not considered a bilateral issue between the UK and Spain.
The DUP showed its anger with Mrs May’s Brexit deal by joining with Labour to cut the Government’s majority to just five in a Commons vote on the Budget.
They also abstained on a series of other amendments to the Finance Bill on Monday night, in a move intended to send a “political message” to the Prime Minister.
Their actions appeared to call into question the future of the “confidence and supply” arrangement by which the DUP props up Mrs May’s minority Conservative Government.
Under the terms of the deal, agreed after Mrs May lost her Commons majority in last year’s general election, the Northern Ireland party is supposed to back the Government on Budget matters and on confidence votes.
But DUP Brexit spokesman Sammy Wilson said Mrs May’s deal with Brussels breached a “fundamental” assurance that Northern Ireland would not be separated constitutionally or economically from the rest of the UK.
“We had to do something to show our displeasure,” he told the BBC.
In a bid to sway opinion, Mrs May has insisted that her draft Brexit deal puts Northern Ireland in a “fantastic position” for the future.
In an opinion piece published in the Belfast Telegraph, the Prime Minister claimed the region’s constitutional status within the UK had been guaranteed in the agreement.
Mrs May acknowledged that there had been a lot of focus on the Irish border “backstop” and said she “understood and share some of the concerns that have been expressed”.
But she said the backstop was an “acceptable insurance policy” due to provisions in the deal.
The DUP warning adds to the pressure on the Prime Minister just as the Tory bid to unseat her by Brexiteers appeared to have stuttered.
Members of the Conservative European Research Group were last week confidently predicting they would get the 48 letters of no confidence needed to trigger a vote in her leadership.
However, there has been no announcement from the chairman of the backbench 1922 Committee, Sir Graham Brady, that they have reached that tally, while the number of MPs who have publicly declared they submitted letters remains in the twenties.
There were also reports that the so-called “pizza club” group of Cabinet Brexiteers was backing away from a plan to go to the Prime Minister to demand she re-opens negotiations with Brussels on a key element of the agreement.
Michael Gove, who last week turned down the job of Brexit Secretary following the resignation of Dominic Raab, Andrea Leadsom, Penny Mordaunt, Liam Fox and Chris Grayling were all reported to be unhappy with the terms over the Northern Ireland border.
However, there was little sign that they were preparing to force a fresh showdown at the weekly meeting of the Cabinet in Downing Street on Tuesday.
Meanwhile, in a further sign of the Government’s weakness, ministers were forced to offer fresh concessions to stave off a damaging defeat over the publication of the Government’s assessment of the economic impact of Brexit.
Treasury Minister Robert Jenrick told MPs they would now release a comparative analysis of the economic impact if Britain was to remain in the EU rather than leave in March 2019.
Previously, the Government had only undertaken to publish its assessment of the impact of leaving with a deal, compared with a no-deal Brexit.