London: Prime Minister David Cameron on Friday promised tough curbs on welfare for EU migrants to counter a surge in arrivals and warned European leaders that resistance could put Britain`s EU membership in doubt.
He said the package of reforms would require changes to existing European Union treaties, something all member states must agree to, but said he was "confident" that they could be agreed.
Immigration to Britain has increased sharply in the past decade, putting pressure on public services, and Cameron is under pressure to address voters` concerns ahead of the May 2015 general election.
His Conservative party is losing support to the UK Independence Party (UKIP), which advocates leaving the EU altogether as the only way to curb EU migration.
In a long-awaited speech on the issue, Cameron stopped short of calling for a cap on new arrivals or a mooted "emergency brake", which had caused consternation in EU capitals.
But he announced plans to make EU workers wait four years to receive income tax credits and access social housing, and vowed to stop them claiming benefits for children living elsewhere in Europe.
Cameron said the reforms, intended to make Britain less attractive, were an "absolute requirement" of his bid to renegotiate Britain`s membership of the bloc before holding an in-out referendum in 2017.
He repeated that he wants Britain to stay in the EU but warned: "If our concerns fall on deaf ears and we cannot put our relationship with the EU on a better footing, then of course I rule nothing out."
Cameron briefed German Chancellor Angela Merkel, Polish Prime Minister Ewa Kopacz and European Commission president Jean-Claude Juncker on his speech beforehand, aides said.
Afterwards, a Commission spokesman said the EU`s executive arm was ready to discuss the proposals "calmly and carefully", adding: "We have to see what can be done without shutting the door."
Benefit tourism and the abuse of social welfare systems have become issues for voters across Europe and Cameron noted concerns about immigration in Germany and Italy.
But Steve Peers, professor of law at the University of Essex, said a number of Cameron`s proposals would require all member states agreeing to change EU treaties.
"That isn`t impossible, but it won`t be very easy," he said.Cameron said Britain had long benefited from immigration and condemned "deeply unpatriotic" calls to shut its borders.
But he said its economic growth and relatively generous welfare system had made it a "magnetic destination" for migrants, and the government had to take back some control.
Cameron was forced to abandon a promise to cut net migration to Britain to under 100,000, after official figures on Thursday revealed it rose from 182,000 to 260,000 last year.
But he insisted action was still possible, and said migrants should have a job before arriving and could be deported if they do not find work after six months.
He also repeated calls for restrictions on the rights of citizens of new EU nations to work in Britain until their economies improved in line with other members.
Many Tories in Cameron`s party responded positively to the speech, including Mayor of London Boris Johnson, but eurosceptics warned it did not go far enough.
UKIP leader Nigel Farage said the measures would likely be challenged in the EU courts.
"While he may have taken away, potentially, one or two of the pull factors, you cannot control immigration as a member of the European Union because we have total open borders with the other member states," Farage told the BBC.
Since it took office in 2010, the coalition government has tightened visa restrictions for non-EU migrants, but European rules on freedom of movement mean it has little control over arrivals from within the bloc.
Reports last month that Cameron was considering a cap on migrant numbers were condemned by the European Commission, and Merkel reportedly warned the prime minister that he was approaching a "point of no return".
Cameron said Friday that freedom of movement was "key to being part of the single market".
But he added: "I say to our European partners -- we have real concerns. Our concerns are not outlandish or unreasonable. We deserve to be heard, and we must be heard."