The forthcoming resignation of Theresa May as prime minister will not change the Withdrawal Agreement previously negotiated with the UK, European leaders warned today.
A spokeswoman for Jean-Claude Juncker said the president of the European Commission had followed Mrs May's announcement this morning "without joy".
She added that Mr Juncker would "respect and establish working relations with any new prime minister, whomever they may be" without stopping his conversations with Mrs May.
Speaking before Mrs May announced her resignation, Mr Juncker asked: "How could anybody else achieve what she couldn't?"
"If you tell people for 40 or 45 years 'we're in it, but not really in it', we're part-time Europeans and we don't like these full-time Europeans, then you should not be surprised if people follow simple slogans once they're asked to vote in a referendum."
The downfall of the prime minister has long been anticipated by Brussels. Last month the European Council reiterated there would be no "reopening" of the Withdrawal Agreement previously agreed by the UK Government and other EU states.
EU leaders will discuss today's developments and how to collectively respond as part of a planned Brussels summit on May 28.
French president Emmanuel Macron said today that he wanted "rapid clarification" from the UK on how the country plans to approach Brexit after the departure of Mrs May.
A statement released by the Elysee Palace added that Mr Macron is ready to work on ensuring an orderly Brexit together with Mrs May's successor but warned that "at a time of important choices, rejection votes without alternative projects lead to an impasse."
In Germany, chancellor Angela Merkel said she noted Mrs May's resignation "with respect".