German Chancellor Angela Merkel called today for clear-headed negotiations with Britain on its departure from the European Union, stressing that talks with the "close partner" must take place in a good atmosphere.

Ms Merkel's reasoned approach came despite a call from foreign ministers from the EU's six founding members for Britain to leave the bloc as soon as possible after Britons voted to quit in the biggest blow to the project since World War Two.

However, Ms Merkel struck a more conciliatory tone.

"The negotiations must take place in a business-like, good climate," Ms Merkel told a news conference after a meeting of her conservative party in Hermannswerder, outside Potsdam to the west of Berlin.

"Britain will remain a close partner, with which we are linked economically," she said, adding that there was no hurry for Britain to invoke Article 50 of the EU treaty - the move it must make to set in motion the process to exit the bloc.

"Quite honestly, it should not take ages, that is true, but I would not fight now for a short-time frame," Ms Merkel said.

To the north of the German capital, the six foreign ministers struck a more urgent tone, pressing Britain to trigger the process for exiting the bloc after Britons voted by 52-48% to exit the EU, which it joined more than 40 years ago.

EU Foreign Ministers

"We now expect the UK government to provide clarity and give effect to this decision as soon as possible," the ministers from Germany, France, Italy, the Netherlands, Belgium and Luxembourg said in a joint statement.

It is up to Britain to set in motion this process to exit the bloc.

The president of the European Parliament Martin Schulz also piled pressure on Britain, calling for it to trigger the Leave process at a summit of EU leaders next Tuesday.

"We expect the British government to deliver now," Mr Schulz told Germany's Bild am Sonntag newspaper. "The summit on Tuesday is the appropriate moment to do so."

EU officials said there was no real problem if it took a few months to begin the process for Britain to leave, though waiting until the end of the year could get in the way of the next round of EU budget talks and European election campaigning.

The officials said they were worried that Mr Cameron could hand over to someone with a strategy to drag out the country's departure.

Matthew Elliott, chief executive of the Vote Leave campaign, said Britain should begin informal negotiations on a full settlement governing its post-Brexit relationship with the EU before invoking Article 50 of the Lisbon Treaty.

Pressure from France             

France also pressed for a swift start to the exit process, with Foreign Minister Jean-Marc Ayrault saying negotiations must move quickly and that the remaining EU member states also needed to give fresh impetus to the European project.

"We have to give a new sense to Europe, otherwise populism will fill the gap," he said, adding that the EU could not wait for Mr Cameron to depart in October before the exit process begins.

Mr Ayrault said other EU leaders would put "a lot of pressure" on Cameron at Tuesday's summit to act quickly.

French President Francois Hollande said the separation: "will be painful for Britain but ... as in all divorces, it will be painful for those who stay behind too."

France and Germany have drafted a 10-page paper mapping out three areas of immediate concern for the remaining EU members: security, migration and refugees, and jobs and growth which diplomatic sources say they want to use as a basis to shore up the EU, while building a more flexible union.