Nordic PMs warn Cameron over EU immigration change
David Cameron has faced warnings from three leaders of Nordic countries over his plans to limit immigration from the European Union.
Swedish Prime Minister Stefan Lofven said a change of rules on free movement could "ruin" the 28-member group.
And Norwegian Prime Minister Erna Solberg said freedom of movement was "very important" to her people.
Mr Cameron has promised to set out his next steps on curbing immigration before Christmas.
It has been reported that the UK could seek to apply an "emergency brake" to reduce net migration - the difference between those entering and leaving - after it reached a certain level, or to limit the number of National Insurance numbers issued to new arrivals.
And Chancellor George Osborne has insisted this week that the country will pursue its "national interest".
But Mr Lofven told the BBC: "The fact that one country believes that one thing is wrong does not mean that we can change because every country might have its own priorities and that may just ruin the European Union.
"I think it's wrong because that means that every country can find their own solutions on different issues. If you first create a common market with common rules and then if the individual countries are supposed to change that on their own, then, I mean, soon, we do not have a European common market."
Mr Cameron is attending a summit of northern European leaders in Finland, whose Prime Minister Alexander Stubb said the principle of freedom of movement was "rather holy", adding that the UK "should be rewarded with an EU medal for bringing forward the holy grail" by opening the borders to Eastern Europe.
Asked for his message to Mr Cameron, he replied: "Thank you for having opened your borders and let's see what we can do about the whole situation to try to alleviate it and facilitate it."
BBC political correspondent Robin Brant
David Cameron would consider himself to be among friends at this, the most informal of formal prime ministerial gatherings.
But even when you've shared roast fillet of reindeer - as they did at a private dinner last night - it doesn't mean you agree on everything.
This time round, the other eight leaders are less sympathetic to his cause, and it was the host who said so.
Finland's Prime Minister Alexander Stubb toned down his language a little. He didn't repeat last week's jibe that Mr Cameron's rage over the £1.7bn payment was "mountains out of molehills".
Instead he told the BBC he could understand why it had become a problem.
Mr Stubb has long been seen as a friend of the UK and a political ally of the Conservatives, having studied at the London School of Economics and married a British woman.
He said: "I have three Brits at home - a wife and two children and, of course, my in-laws. My mother-in-law and father-in-law are retired teachers and my sister-in-law is a teacher in a school which has a lot of Central and East European students, so I have seen it close up."
Norway's Ms Solberg said the free movement of people was "extremely important to Norway" and the principle was "ideologically important as a conservative".
Norway is not a member of the EU, but the country is a participant in the single market and therefore allows the free movement of EU citizens.
But former UK Chancellor Ken Clarke, one of the most pro-European voices in the Conservative Party, said the UK would lose all influence if it left the EU and accused eurosceptics of "synthetic anger" on a wide range of issues.
"If you want to keep the EU intact as an economic entity, you have to pay your contributions and you have to have free movement of labour," he told the BBC. "Norway pays a contribution, Norway has free movement of labour.
"But we are in the EU, we can go the Council of Ministers, negotiate and argue about these things. Poor Norway has to be told what was decided afterwards."