The European Union will not hold informal talks with the UK until it triggers Article 50 to leave, Germany, France and Italy have insisted
ll three leaders voiced regret at the UK's vote to leave, with Mrs Merkel calling it a "very painful and regrettable decision".
"We are in agreement that Article 50 of the European treaties is very clear - a member state that wishes to leave the European Union has to notify the European Council," Mrs Merkel told the joint news conference at the German chancellery.
"There can't be any further steps until that has happened. Only then will the European Council issue guidelines under which an exit will be negotiated.
"That means that, and we agree on this point, there will be neither informal nor formal talks on a British exit until the European Council has received the [UK's] request for an exit from the European Union."
President Hollande and Prime Minister Renzi emphasised the need to process the UK's exit as quickly as possible and focus on the challenges facing the remaining 27 states such as fighting terrorism and strengthening the borders.
"Our responsibility is not to lose time in dealing with the question of the UK's exit and the new questions for the 27," Mr Hollande said. "There is nothing worse than uncertainty."
Labour crisis: Parliamentary Labour Party to go ahead with no confidence vote in Jeremy Corbyn after 35 shadow ministers quit
Jeremy Corbyn has lost more than half his Cabinet and seen more than 30 of his MPs revolt against his leadership over the last 48 hours.
Mr Corbyn has lost 20 of his 31 strong shadow cabinet and seen a further 13 shadow ministers resign this morning.
The rebels have criticised his performance in the EU referendum and he faces further resignations from the junior frontbench ranks amid fresh calls for him to stand down as leader.
Jeremy Corbyn's grip on the Labour leadership looked increasingly weak as Angela Eagle became the most senior member of his shadow cabinet to quit.
Shadow housing minister John Healey, shadow energy secretary Lisa Nandy and shadow work and pensions secretary Owen Smith have all resigned - adding to the 12 shadow cabinet members Mr Corbyn lost on Sunday.
Sources said that Mr Corbyn will refuse to step down and will instead try and make public a planned secret vote on his future so that voters can see which MPs are trying to unseat him.
David Cameron has ruled out a second referendum on Britain’s EU membership.
The Prime Minister’s spokesperson said that holding another vote was “not remotely on the cards”. The clarification comes amid a petition calling for a re-run in the event of a close result and following speculation that the government may go to the country again once the terms of Britain’s new relationship have been agreed.