British Prime Minister David Cameron secured encouraging signals from the leaders of Germany, Hungary and the Netherlands as he swung through Europe Thursday, despite key reservations over an EU reform deal he wants at a summit next month.

Cameron held talks with Hungarian Prime Minister Viktor Orban -- who expressed optimism about a deal even as he denied his countrymen were "parasites" seeking British welfare benefits -- and the leaders of German Chancellor Angela Merkel's sister party.

The British premier is battling for a deal at an EU summit in February before holding a referendum on Britain's membership of the bloc, possibly later this year, but he faces opposition to his controversial demand to limit benefits for EU migrants.

Orban, a polarising figure in Europe for his own right-wing anti-immigrant politics, said Hungary "fully supported" three out of Cameron's four demands, adding that he had "reason to be optimistic to find a common agreement".

Cameron's other demands are for the European Union to give Britain safeguards against more political integration, to protect countries that do not use the euro currency, and to boost economic competitiveness.

But Cameron's final demand -- a four-year delay before EU migrants working in Britain can claim welfare benefits -- was "difficult" amid concerns in many countries that it is discriminatory, Orban told a press conference with Cameron.

"We are citizens of a state that belongs to the EU, that can take jobs anywhere in the EU, so we don't want to go the UK and take something away from them, we don't want to be parasites," Orban said.

Cameron laid out his plans to fellow EU leaders at their last summit meeting in December, urging them to help him to make the reforms and avoid a "Brexit" from the 28-nation bloc.

Speaking in Budapest, Cameron said the welfare plans remained on the table but that he was "open to alternative solutions", while holding out the possibility that a deal could take longer than the February summit.

"We obviously now have a limited time between now and the February (EU) Council, I am confident that if we work hard with goodwill on all sides we should try for an agreement," he said.

"But as I said I only have to hold my referendum by the end of 2017. If it takes longer to make an agreement, what matters to me is the substance rather than the timing," he added.

Cameron has vowed to hold the in-out referendum by the end of next year but British media have reported he could hold the vote as soon as June 2016 if he gets a deal at February's summit.

In Germany, Cameron met Merkel over dinner in Berlin on Wednesday and on Thursday held talks in the southern town of Wildbad Kreuth with the Christian Social Union -- sister party of the chancellor's CDU.

While Merkel is seen as generally supportive of Britain's position, she has said that "fundamental achievements of European integration" are not up for debate -- including the core principle of freedom of movement.

However Merkel later Thursday acknowledged that it was "not the intention of the law of free movement" to allow EU migrants to claim benefits from host member states immediately.

"That means that you can work everywhere in Europe but this intention does not include drawing social benefits everywhere in Europe from day one," she said.

Dutch Prime Minister Mark Rutte, whose country assumed the EU presidency this month, said Thursday he was "relatively optimistic' that Britain can secure a deal in February.

"It is very important to come to a successful conclusion, I think we could get there in February, I am relatively optimistic," Rutte said at a press conference in Amsterdam alongside European Commission chief Jean-Claude Juncker.

"But still a lot of work needs to be done to come to a decision and a conclusion in February," added Rutte, under whom the Netherlands will hold the presidency of the European Union for the next six months.