British Prime Minister David Cameron has pledged to stop new arrivals from the EU getting out-of-work benefits for three months as he seeks to allay fears over easing controls on Romanian and Bulgarian immigrants.
Mr Cameron set out plans to tweak British welfare rules as he admitted he shared concerns about the end of transitional restrictions for the latest member states next year.
He also demanded wider EU reforms for the future, suggesting labour movement from countries joining the EU could be limited until they hit a certain level of GDP per head.
The intervention, in an article for the Financial Times, comes amid calls from dozens of Conservative Party MPs for the government to ignore European law and extend controls on Romania and Bulgaria until 2018.
Mr Cameron said the Labour party's failure to keep tougher limits on countries such as Poland in 2004 had been a "monumental mistake" and he "shared concerns" about what would happen after 1 January.
"We are changing the rules so that no one can come to this country and expect to get out of work benefits immediately; we will not pay them for the first three months," he said.
"If after three months an EU national needs benefits - we will no longer pay these indefinitely. They will only be able to claim for a maximum of six months unless they can prove they have a genuine prospect of employment.
"We are also toughening up the test which migrants who want to claim benefits must undergo.
"This will include a new minimum earnings threshold. If they don't pass the test, we'll cut off access to benefits such as income support. Newly-arrived EU jobseekers will not be able to claim housing benefit."
British government aides said currently some immigrants could access Job Seeker's Allowance within a month of arrival in the UK.
Mr Cameron said migrants found begging or sleeping rough could be deported.
"They will then be barred from re-entry for 12 months, unless they can prove they have a proper reason to be here, such as a job," he said.
Firms that pay less than the minimum wage will face fines of up to £20,000 (€23,800) in an attempt to prevent undercutting of British workers.
Mr Cameron's comments drew a rebuke from the European Commission, which said his intervention was "an unfortunate over-reaction".
European Commissioner for Employment and Social Affairs Laszlo Andor said the kind of "unilateral rhetoric" Mr Cameron was using on immigration was unhelpful.
"This is an unfortunate over-reaction. We would need a more accurate presentation of the reality, not under such hysteria, which sometimes happens in the UK," he told the BBC.
"Unilateral rhetoric ... is not really helpful. It risks presenting the UK as a kind of nasty country. We have to look into the situation collectively and act proportionately."
