Sensing a looming row over the Brexit timeframe, German Chancellor Angela Merkel appealed for calm on Saturday.

“It shouldn’t take forever, but I wouldn’t fall out over a short time period,” she said. “I take it that in Britain there is a wish to deal with the referendum by implementing the result.”

She played down suggestions that remaining EU states would want to punish the UK for its decision, saying there was “no need to be particularly nasty in any way in the negotiations”.

In contrast, Britain was ordered to get out of the EU without delay at a meeting of the EU’s founding member foreign ministers on Saturday outside Berlin.

As the dust began to settle on the Brexit decision, chief diplomats from Germany, France, Belgium, Luxembourg, Italy and the Netherlands made clear that their focus now on the EU, not Britain.

“We understand and respect the result and understand that Britain is now concentrating on Britain,” said Mr Frank-Walter Steinmeier, host of the back-to-the-roots meeting. “But London has a responsibility toward more than just Britain. We must now be allowed to focus on the future of Europe. ”

On Friday, departing British prime minister David Cameron suggested that London would the first step in divorce proceedings would come under his successor - by October at the latest. But European Commission president Jean-Claude Juncker told German television on Friday night that it made “no sense” to hang around until October and that he expected Britain’s farewell letter on his desk “immediately”.

The six ministers meeting outside of Berlin agreed, one after another, that they had no interest in allowing a political vacuum develop and wanted Britain out of the EU sooner rather than later.

Luxembourg’s foreign minister Jean Asselborn warned London not to start a damaging “game of cat and mouse” by stalling Brexit negotiations, saying: “The people have spoken and we need to implement this decision.”

Echoing his colleagues’ remarks, Dutch foreign minister Bert Koenders said that “this will not be business as usual” for Europe.

French foreign minister Jean-Marc Ayrault said Paris expected movement “in a few days” to begin exit procedure under article 50 of the Lisbon Treaty.

The ministers showed a striking lack of sympathy for Mr Cameron, but the French minister was perhaps most forthright. After taking a chance by calling the referendum, Mr Ayrault said Mr Cameron “now needs to live with the consequences.”

The difference in tone between Mr Steinmeier and Dr Merkel indicated growing friction between Berlin’s grand coalition partners and raises the prospect of a clash at next week’s EU summit between leaders from Europe’s conservative and socialist camps.

While Dr Merkel, head of the centre-right Christian Democratic Union (CDU), has struck a conciliatory note, Mr Steinmeier’s centre-left Social Democrats (SPD) have lashed out at Britain’s decision.

European Parliament president Martin Schulz, a German SPD member, said it was “scandalous” that Britain was holding out until October for talks and accused Mr Cameron of “taking a whole continent hostage for internal (Tory) party considerations.

Together with SPD leader Sigmar Gabriel, deputy chancellor in Berlin, Mr Schulz has put forward a 10-point EU reform plan proposing more powers for the EU and national parliaments, and criticising the closed-door meetings in Brussels attended by Dr Merkel and other EU leaders.

On his way into the Saturday meeting, Mr Steinmeier declined to confirm reports that Berlin and Paris will present proposals next week for a “flexible” union, allowing member states more leeway on their degree of European integration. However he added that “it is clear that Europe needs to deliver solutions the people are asking for”.

The major issues of the day, he said, were refugees immigration, youth unemployment and security concerns.

Following widespread appeals for unity on Friday, Saturday’s invitation-only meeting in Berlin raised hackles among those not in attendance. Estonian president Toomas Hendrik Ilves, wrote on Twitter: “If EU 27 unity now a priority then the meeting of EU ‘founding six’ is not quite on message.”