British Prime Minister Theresa May will travel to Brussels on Monday to meet with European Commission President Jean-Claude Juncker, ahead of a decisive EU summit this week.
May will be joined by her Brexit Minister David Davis for the dinner to discuss Thursday's summit of EU leaders -- where Britain's departure from the block will be high on the agenda -- the source said.
Broader European and geopolitical issues will also be on the table at the meeting, which will be attended by May's Brexit adviser Olly Robbins and Juncker's cabinet chief Martin Selmayr, an EU source told AFP.
While Downing Street insisted the meeting has been in the diary for weeks, the British premier's arrival in Brussels brings with it a sense of urgency after last week's disappointing Brexit talks.
The fifth round of discussions ended on Thursday with EU negotiator Michel Barnier, who is also expected at Monday's dinner, warning the two sides were at an "extremely disturbing" deadlock over Britain's Brexit bill.
Brussels has insisted on reaching progress on its three priorities -- the exit bill, citizens' rights, and the border with Ireland -- before moving on to talks of a future relationship with London.
The British government had hoped to have achieved sufficient progress in the negotiations by the upcoming summit in order to press on with discussions of a future partnership, but Barnier said last week he "cannot recommend" such a step forward.
The Europeans are therefore set to disappoint Britain at the summit by saying there has not been enough progress to move on to trade talks until December at the earliest, according to a draft statement obtained by AFP.
But the leaders of the 27 remaining EU countries are expected to extend an olive branch to May, by saying that Brussels should start internal preparations for talks on the future relationship with Britain.
The British prime minister will arrive in Brussels after a period of turbulence at home since losing her Conservative Party's parliamentary majority in June after calling a snap election.
There have since been frequent reports of cabinet infighting over Brexit and, earlier this month, May fought off a plot by around 30 Conservative MPs to oust her from power.
With EU negotiations flagging, May last week told the British parliament that her government is setting money aside to prepare for Brexit -- including for a no-deal scenario.
Britain is due to leave the bloc on March 29, 2019, although in practice a deal will have to be reached months earlier to give the European Parliament time to discuss the agreement.