European Union president Donald Tusk said on Friday that the bloc is determined to stay unified after Britain voted to leave, and warned against "hysterical" reactions.
"Today on behalf of the 27 leaders, I can say that we are determined to keep our unity as 27," Tusk told reporters in Brussels.
"It is a historic moment but for sure not a moment for hysterical reactions."
Britons voted 51.9 percent to 48.1 percent in favour of leaving the bloc, upsetting the odds and sending shockwaves around the world as markets and pundits alike got caught out badly by the result.
Tusk, who had earlier warned that a Leave vote could "end Western political civilisation", said he wanted to assure EU citizens that their leaders were prepared all the same.
He said there would be no legal vacuum and that all the procedures for Britain leaving the EU were clearly laid down in the treaties.
The 27 EU leaders will hold an informal meeting on the sidelines of a summit next week where Tusk said he would "propose that we start a wider reflection on our Union".
Eurosceptic sentiment has grown steadily in recent years, largely in opposition to the austerity programmes imposed by Brussels, and Tusk has regularly warned against the dangers of anti-EU sentiment.
But in a brief appearance before the press, Tusk stressed that there was no reason for despair.
"It is true that the past years have been the most difficult ones in the history of our Union, but I always remember what my father used to tell me -- 'What does not kill you make you stronger,'" he said.