Ahead of his visit, the Polish Minister for European Affairs spoke to the BBC's Chris Morris.

Rafal Trzaskowski said that while Poland would consider what Mr Cameron had to say, any EU treaty change would be very difficult.

"The European Union needs Great Britain... but the discussion will not be easy. Introducing something that will clearly be discriminatory, that's a red line for Poland," he said, in a veiled reference to Mr Cameron's call for restrictions on migrants' benefits.

One of Cameron's key demands in the renegotiation is cutting welfare payments to EU migrants in Britain. Around 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 Schetyna told public broadcaster TVP1 on Friday.

"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."

Cameron met Polish Prime Minister Ewa Kopacz on Friday morning and is then due to head to Berlin for talks with German Chancellor Angela Merkel.

"As far as treaty changes are concerned or the introduction of discriminatory measures, that would be a red line for Poland, Poland's Minister for European Affairs Rafal Trzaskowski told the BBC.

"If every country comes with a shopping list to change European Union policies, that will be the end of the European construction, it will simply implode."

Volker Treier, deputy chief executive of Germany's chamber of commerce and industry, expressed a similar view. He told the BBC Merkel should not offer Britain concessions because it would encourage other countries to demand changes to their terms of membership.