Cameron met with Poland's influential government party leader Jaroslaw Kaczynski on Friday, who gave his blessing to the UK's proposed pact to curb welfare for new migrant workers from EU countries.

The proposals will allow British authorities to withhold in-work social security benefits for up to four years from EU citizens moving to Britain.

The plans are controversial as Poland is the biggest source of Britain's migrant labor force.

But Kaczynski insisted that British officials had guaranteed to preserve the rights of the estimated 600,000 Poles already working in the UK.

Later on Friday, Cameron also received broad support for his reforms from Danish Prime Minister Lars Lokke Rasmussen during a visit to Copenhagen.

"I support all the elements regarding welfare benefits," said Rasmussen, whose center-right government needs the backing in parliament of the euroskeptic, anti-immigration Danish People's Party.

The British leader traveled to the two capitals as part of a diplomatic tour of Europe to attempt to keep the UK in the EU after promising the British electorate that he would secure substantial reforms within the 28-member bloc.

He needs to convince all European leaders to back his proposals before the next European Council summit later this month.

Cameron's plans would also give London an opt-out from moves towards further political union and ensure safeguards to prevent Britain from being disadvantaged by remaining outside the euro currency zone.

June vote expected

Cameron has promised British voters an in-out referendum on the UK's membership of the EU, which is widely expected in June.

A new YouGov opinion poll for the Times newspaper showed the campaign for Britain to leave the EU has taken a nine-point lead over the rival "remain" campaign, while 19 percent said they did not know or would not vote.

But a similar ComRes poll last week showed the "in" campaign held an 18-point lead over those who wanted out.

European politicians are divided on the 'Brexit' deal, with some saying the proposals don't go far enough.

EU negotiators held their first discussion on the package in Brussels on Friday, which officials said threw up no roadblocks. Attempts to reach a deal will also follow at a summit of EU leaders beginning February 18.

The US and Germany have repeatedly said they want Britain to remain within the EU.

But European Parliament President Martin Schulz warned on Friday that the UK could not expect "Europe a la carte," where countries could ignore aspects of the EU they did not like.

"Many of my colleagues say behind closed doors: 'Don't stop a rolling stone. If the Brits want to leave, let them leave,'" he told students at the London School of Economics.

"But Europe needs the UK with its foreign policy experience and clout, its open market policies and its trade track record."

mm/gsw (AFP, Reuters)