London, Jun 27 (IANS): The European Union and Britain on Monday appeared to be heading for a stalemate over the bloc's summit slated for Tuesday to discuss UK's vote to leave, the Guardian reported.

With Europe's leaders divided over how to negotiate Britain's exit -- Brexit -- and London apparently reluctant to initiate formal talks on leaving, an EU source said lawyers had concluded that a member state could not be forced to launch the process.

But another senior EU official said that, by the same token, Brussels could refuse overtures for even informal talks before the exit process is officially initiated -- a course that prominent Brexit leaders, including former London Mayor Boris Johnson, want to pursue.

"As long there is no notification, there will not be any negotiations," the official said.

Brussels has given up hope that Britain could be bounced into triggering article 50 -- the untested procedure that governs how a member state leaves the bloc -- at the upcoming summit.

US Secretary of State John Kerry is due in London for talks later on Monday after a stop-off in Brussels, while the leaders of Germany, France and Italy will meet in Berlin.

Kerry has urged both Britain and the EU to "minimise disruption" by negotiating the divorce responsibly.

Prime Minister David Cameron is due to explain Britain's position at a dinner at the EU summit on Tuesday night. Cameron will leave after the dinner, taking no part in the talks between leaders of the bloc's 27 remaining members on Wednesday.

President of the EU parliament Martin Schulz led the call for formal exit talks to be launched as early as Tuesday.

"We expect the British government to deliver now," he told Germany's Bild am Sonntag daily.

"The summit on Tuesday is the appropriate moment to do so."

European Commission President Jean-Claude Juncker said talks should start as a matter of urgency. He had called Cameron on Friday to say the prime minister should trigger article 50 immediately.