By William James
BERLIN (Reuters) - British Prime Minister David Cameron meets German Chancellor Angela Merkel on Friday in an attempt to gauge how far Berlin will go to keep the world's fifth-largest economy inside the European Union ahead of a referendum on membership.
Cameron's post-election tour of European capitals ends with a lunch at which he is likely to ask Merkel's help in securing a deal of concessions that he could sell to a divided British public before the referendum by the end of 2017.
French President Francois Hollande told Cameron on Thursday he wanted Britain to stay in the world's biggest trading bloc while Cameron said the status quo in Europe was "not good enough".
"My priority is to reform the European Union to make it more competitive and address the concerns of the British people about our membership. The status quo is not good enough," Cameron said.
Cameron met Polish Prime Minister Ewa Kopacz on Friday morning but Warsaw said it would be firm over the rights of Polish migrants in Britain and that it would not countenance treaty change, a key British demand.
About 800,000 Poles live in Britain, as well as many other Eastern Europeans.
"We want Great Britain to stay in the EU. But the interest of Poles, our citizens who live in Great Britain is important," Foreign Minister Grzegorz Schetyna told public broadcaster TVP1.
"It's a question of the joint market, these are basic questions. We understand the British stance. But there are also EU fundamentals on which joint Europe was forged. It will be a tough conversation, but very firm on the Polish side."
A spokesman for Cameron said the Polish prime minister agreed that Europe should be made more competitive but that both leaders agreed there were issues around the free movement of people that should be discussed further.
Cameron, whose preference is to stay in a reformed European Union, has said the relationship is not working in Britain's interest and that it would not break his heart to leave the EU.
Cameron will set out his reform proposals in more detail at an EU summit on June 25-26.
Some EU countries have made clear they have no appetite to re-open the bloc's treaties to suit Britain, which wants to alter them so it can restrict and delay EU migrants' access to its welfare system.
But London has long asserted that the treaties would need to be overhauled anyway as part of an inevitable drive to further integrate the euro zone.
In a potential setback for Cameron, a Franco-German paper seen by Reuters shows the two countries have agreed plans to strengthen cooperation among the 19 countries using the euro currency, without changing existing treaties.
(Writing by Guy Faulconbridge; Editing by Angus MacSwan)