The leaders of France, Germany, Spain and Italy have called for a European Union which allows groups of member states to advance at their own pace.
French President Francois Hollande hosted his counterparts on Monday (March 6th) evening in Versailles, near Paris, to prepare for a larger EU meeting later this week.
"Europe must be able to draw the consequences of the Brexit", he said in a joint statement with the other leaders of the European Union's major economies.
The leaders said the bloc could lose its momentum without the changes they propose, and Hollande has warned the future of the union itself is at stake.
Mr Hollande said: "Unity is not uniformity and this is the reason why I call for new forms of cooperation (...) that we could go quicker and stronger with some countries without excluding others and without having others who can oppose."
Germany's Chancellor Angela Merkel added: "We must have the courage that some countries precede if not all want to participate: a Europe of different speeds is necessary, otherwise we will probably get stuck."
The two leaders were joined by Italian Prime Minister Paolo Gentiloni and Spanish Prime Minister Mariano Rajoy for talks at the opulent palace near Paris.
Their meeting comes ahead of an EU Council meeting in Brussels this week and the 60th anniversary of the Treaty of Rome on March 25th.