File photo of David Cameron.
British Prime Minister David Cameron met Poland's premier in Warsaw Friday on a whistlestop European tour to gather backing for EU reforms but faced implacable Polish opposition to proposals to limit benefits for immigrants.
Cameron was due to go on to Berlin later in the day to lobby German Chancellor Angela Merkel.
Among changes Cameron is seeking are tougher requirements for EU migrants to claim state benefits in Britain. He also wants Britain to be able to opt out of a commitment to "ever closer union"
Polish Prime Minister Ewa Kopacz, however, has warned Cameron that his reforms "cannot discriminate against Poles".
Over 800,000 live and work in Britain and she has said "it would be a shame" if it "were to disappear from the EU."
The second day of Cameron's European tour came as his government published a law paving the way for a referendum on whether Britain should leave the EU that must be held by the end of 2017.
The prime minister has moved rapidly after securing a mandate for EU reform following his surprise election win earlier this month.
The British premier intends to speak to every EU leader before a summit in Brussels next month where the proposed British reforms will be discussed in more detail.
"The status quo is not good enough and I think there are changes that can be made that can benefit not just Britain but the rest of Europe too," Cameron said before a dinner with French President Francois Hollande in Paris on Thursday.
"My priority is to reform the European Union to make it more competitive and to address the concerns that British people have about our membership.
"We want to help the euro zone work better."
Hollande said that France wanted Britain to remain in the European Union, but that "it will be up to the British people to choose their future."
"David Cameron will present his proposals and we will discuss them and see how we can move forward," he added.
Cameron also met his Dutch counterpart Mark Rutte for lunch in The Hague on Thursday.
- '27 nuts to crack' -
Before he set off, a British official said there were "27 nuts to crack" to secure concessions.
Cameron said earlier this week he was "confident" of securing a deal, but warned there would be "lots of noise, lots of ups and downs along the way".
Cameron argues that the EU should be retreating from further integration instead of embracing it, and that Europe risks a no vote in Britain by failing to change.
However, a proposal from Berlin and Paris for a summit next week on the future of the 19-member single currency not only mentions tightening ties in the eurozone, but doing so without changing the existing treaties that govern the EU.
And in a sign of Europe's discomfort with the looming referendum, French Foreign Minister Laurent Fabius warned Thursday that the vote was "very risky" and "quite dangerous".
Fabius added that you could not "join a football club and decide in the middle of the match we are now going to play rugby".
Foreign Secretary Philip Hammond said there would need to be "a substantial package of reform" on Europe.
"If we are not able to deliver on these big areas of concern that the British people have, we will not win the referendum when it comes," he told BBC radio.
"What matters is that the European Union and its 28 members are flexible and imaginative about responding to these issues," Cameron said Thursday.
If Cameron can secure the concessions he wants, he will campaign to stay in the EU. Most opinion polls currently suggest voters would also back remaining part of the bloc.
- 'Sooner the better' -
No precise date has been set for the referendum in which British voters will be asked: "Should the United Kingdom remain a member of the European Union?"
The question emerged in the EU Referendum Bill, which was formally laid before parliament and will be debated by the House of Commons for the first time on June 9.
Europe Minister David Lidington told reporters in London that the mood in the government was "the sooner the better" but that this should not come at the expense of getting negotiations right.
While he has faced repeated questions about when he will outline a clear programme of demands, Lidington said he had advised Cameron to do no such thing.
"My advice to my boss would be on no account publish a full negotiating position because I don't think that's sensible in any sort of negotiation at all to set all that out in advance in writing," he said.