German Chancellor Angela Merkel was hosting EU President Donald Tusk and the leaders of France and Italy on Monday for emergency Brexit talks, amid divisions on whether to pressure Britain into a quick divorce.
Merkel has attempted to rein in pressure from within Europe for London to move quickly to invoke Article 50 of the Lisbon Treaty, which would trigger a two-year period to negotiate Britain's departure from the 28-member bloc.
"We cannot afford a deadlock, ... but I have some understanding for the fact that Britain is taking a certain amount of time to analyse the situation," Merkel said during a press conference Monday.
There will be no informal talks about the modalities of Brexit until Britain gives formal notice to the EU by invoking Article 50, she added.
In announcing his resignation on Friday, British Prime Minister David Cameron said he would leave the decision to initiate Article 50 to his successor, who he said was unlikely to be chosen before his Conservatives' party conference in October.
Cameron reiterated this stance on Monday, telling lawmakers that Britain would not give formal notice "at this time," as it must first "determine the kind of relationship we want with the EU."
US Secretary of State John Kerry warned the EU against a "revengeful" approach and called on leaders to act in a "responsible, sensitive" and strategic manner.
"I think it is absolutely essential that we stay focused on how, in this transitional period, nobody loses their head, ... people don't start ginning up scatterbrained or revengeful premises," Kerry said during a visit to Brussels.
Earlier Monday, Tusk met with French President Francois Hollande in Paris. Both were expected to join Merkel and Italian Prime Minister Matteo Renzi for discussions and a working dinner in Berlin later in the day.
Renzi, speaking in the Italian Senate before flying to Berlin, said that "the last thing Europe should do is embark on a discussion on procedures for a year."
This week's EU summit should "be about the relaunch" of the European project and "not just about exit procedures" for Britain, Renzi said.
French Foreign Minister Jean-Marc Ayrault said on the weekend that divorce proceedings with the EU should be triggered in the coming days, but Merkel said later that rushing into an exit would be unwarranted.
In an interview with broadcaster France 2, French Finance Minister Michel Sapin said "there is no difference between France and Germany" regarding the timeline for Britain's withdrawal.
"Should Great Britain go quickly? Yes. France, like Germany, says that Britain has voted [and that] Brexit should be implemented starting now," he said.
There were also tensions within Germany's ruling coalition about how to handle Brexit proceedings, with the centre-left Social Democrats (SPD) brushing aside Merkel's call for a softer line towards Britain.
Merkel, Hollande and Renzi will attend an EU leaders summit in Brussels on Tuesday and Wednesday. The possibility of Britain handing off its EU presidency, due to take place in the second half of 2017, will also be discussed at the summit, an EU source said.