German Chancellor Angela Merkel has said the European Union has "no need to be particularly nasty in any way" in the negotiations with Britain about its exit from the bloc.

She insisted that deterring other countries from leaving the EU should not be a priority in the talks.

And she added she was not in favour of pushing for a speedy withdrawal.

Britain narrowly voted to end its membership in a historic referendum last Thursday.

Merkel was speaking after several EU foreign ministers - including Germany's - had urged Britain to quickly implement its exit.

"It shouldn't take forever, that's right, but I would not fight for a short timeframe," she said.

She added that she was seeking an "objective, good" climate in the talks with Britain, which "must be conducted properly".

German Foreign Minister Frank-Walter Steinmeier had earlier said negotiations should begin as "soon as possible".

He made the comments after an urgent meeting of the six EU founder members to discuss the decision.

British Prime Minister David Cameron has said he will step down by October to allow his successor to conduct talks.

The six countries attending the summit in Berlin - Germany, France, Italy, Belgium, Luxembourg and the Netherlands - first joined forces in the 1950s and still form the core of the EU.

"We say here together, this process should get under way as soon as possible so that we are not left in limbo but rather can concentrate on the future of Europe," Steinmeier said.

His Dutch counterpart Bert Koenders said the continent could not accept a political vacuum, saying "this will not be business as usual".

The UK must now invoke Article 50 of the EU Lisbon Treaty, which sets out a two-year timetable for negotiations on withdrawal.

European Commission head Jean-Claude Juncker said the EU-UK split was "not an amicable divorce", but nor had they had a "deep love affair". He has also said exit negotiations should begin immediately.

"Britons decided yesterday [Thursday] that they want to leave the European Union, so it doesn't make any sense to wait until October to try to negotiate the terms of their departure," Juncker said in an interview with Germany's ARD television network.

Leaders of Eurosceptic parties in France, the Netherlands and Italy quickly demanded referendums in their own countries.