Chancellor Angela Merkel vowed Friday Germany would play a "constructive" role to help keep Britain in the EU and work with Prime Minister David Cameron to reform the 28-nation bloc.
Offering a warm and conciliatory tone to visiting Cameron -- who had received mixed welcomes elsewhere on a two-day European whistlestop tour -- she said Berlin was open to a compromise on London's demands.
"Where there's a will, there is a way," said Merkel, stressing that Germany would not rule out changing EU founding treaties, a tricky issue since it requires approval by all member states.
As both sides discuss a list of issues, "you cannot say that treaty change is a total impossibility," she said at a joint news conference.
Cameron, after his second-term election win this month, has vowed to push strongly for EU reforms and "a better deal for Britain" ahead of an in-out membership referendum he has promised by 2017.
Merkel said that "on the German side there is a clear hope -- and of course this will be decided by the British people -- that Britain will stay on as a member of the European Union".
An upbeat Cameron said that "today was an opportunity to really get down to business and to work through each issue", adding that "of course there is no magic quick solution" to the bundle of issues under discussion.
"The European Union has shown before that when one of its member states has a problem that needs sorting out, it can be flexible enough to do so, and I have every confidence that it will do so again," he said.
'Constructive, productive, friendly'
Cameron was in Berlin as part of a European charm offensive that earlier took him to The Hague, Paris and Warsaw, to sell his shopping list of proposed reforms.
These included stricter requirements for EU migrants in claiming British social welfare benefits, and for London to be able to opt out of an EU commitment to "ever closer union".
Merkel said Berlin and London saw eye-to-eye in many fields, such as on the need to cut EU red tape, and that their talks Friday had been "constructive, productive and friendly".
The leader of Europe's biggest economy said that "we want to play a constructive role as Britain embarks on its process towards a referendum and changes regarding its membership of the European Union".
On the issue of preventing EU migrants from abusing state welfare, she said change "may also be in Germany's interest", and that Berlin was now closely watching relevant European court cases.
The tone was positive despite the fact Cameron's stance conflicts with Franco-German hopes for a more integrated EU and eurozone.
Paris and Berlin seek common fiscal governance in the 19-member single currency union, of which Britain is not a member.
Next Monday Merkel, French President Francois Hollande and European Commission president Jean-Claude Juncker will meet in Berlin to discuss strategy as the threat of a "Brexit" looms.
EU powers want Britain to stay in the EU, given its role as a global commercial power with diplomatic and military muscle -- and the incalculable symbolic damage its departure would do to the EU's global standing.
But impatience has risen in continental Europe about what some see as London's demands for special treatment and "a la carte" EU membership.
French Foreign Minister Laurent Fabius said Thursday that you cannot "join a football club and decide in the middle of the match we are now going to play rugby".
'Brexit a dead-end road'
In Poland on Friday Prime Minister Ewa Kopacz warned Cameron that his reforms on EU migrants "cannot discriminate against Poles", over 800,000 of whom live and work in Britain.
She said "it would be a shame" if Britain "were to disappear from the EU".
Britain has not yet outlined its precise list of reform proposals, to be discussed in detail at a Brussels summit next month.
No date has been set for the controversial referendum, but Britain's Europe Minister David Lidington has said the mood was "the sooner the better".
Analysts say it should be held well ahead of 2017 when Germany and France face elections and their governments will be in no mood for compromises.
Meanwhile a leading German business lobby on Friday made an impassioned plea for Britain to stay in the EU.
"Only a united Europe can remain successful in the world -- divided we will fade into insignificance," said Markus Kerber, chief executive of the Federation of German Industry.
"A Brexit would lead all of us up a dead-end road."