EU leaders pressured Britain Saturday to make a quick exit from the union, warning they could not afford to be left in "limbo" and that the divorce would not be "amicable".
Foreign ministers of EU's founding member states, gathering in Berlin for crisis talks after Britain's shock referendum outcome, said London must begin the process of leaving "as soon as possible".
France's Jean-Marc Ayrault went as far as to call for David Cameron, who has said he would resign by October, to make way fast for a new British prime minister to manage the transition out of the union.
As the EU grappled with the first defection in its six-decade history, European Commission chief Jean-Claude Juncker warned London against foot-dragging now that it had made its fateful choice.
He admitted that the EU had hoped Britain would stay but that now it was key to make the separation process as speedy and painless as possible.
"It is not an amicable divorce but it was also not an intimate love affair," he said.
European Parliament President Martin Schulz called Cameron's decision to possibly wait until October to leave "scandalous", saying that he was "taking the whole (European) continent hostage".
It will fall to Cameron's successor to lead the complex negotiations under Article 50 of the EU's Lisbon Treaty which sets out a two-year timeframe to leave.
German Foreign Minister Frank-Walter Steinmeier, hosting his counterparts from the five other original EU states, said they agreed that London must begin the exit process immediately.
"We join together in saying that this process must begin as soon as possible so we don't end up in an extended limbo period but rather can focus on the future of Europe and the work toward it," he told reporters.
"We understand and respect the result (of the referendum) and understand that Britain is now concentrating on Britain," Steinmeier said, flanked by Ayrault, the Netherlands' Bert Koenders, Italy's Paolo Gentiloni, Belgium's Didier Reynders and Luxemburg's Jean Asselborn.
He insisted London still had a "responsibility" toward the EU.
"We must now be allowed to focus on the future of Europe and that means that after the decision taken in Britain, the process by which we negotiate Britain's exit must begin."
Koenders called for "good faith" talks with London to begin right away: "We have to move on... we need to turn the page."
Characteristically cautious, German Chancellor Angela Merkel said only that Britain's exit talks should not "drag on forever" and that until they were completed, Britain would remain a full-fledged EU member "with all the rights and responsibilities".
Steinmeier had opened the meeting with a heartfelt plea for the EU to remain united even in crisis.
"I am confident that these countries can also send a message that we won't let anyone take Europe from us," he said.
Later in a joint statement, the ministers defended the EU's "long and successful" path since its humble beginnings in 1957.
But they acknowledged that the union needed to address the fact that "parts of our societies are not happy with how the EU works at the present time".
"The European Union stands before enormous challenges in a globalised world, which only a better European Union can grapple with," they wrote, citing migration and refugees, security, economic growth and jobs as key priorities.
They also acknowledged that among the remaining 27 member states there were differing "levels of ambition" for European integration and had "to find ways to better deal with" them.