Downing Street today welcomed a draft deal to reform Britain's membership of the EU - paving the way for an in/out referendum in June.
European Council president Donald Tusk published the interim agreement following months of intensive talks between UK and Brussels officials.
The key section would allow Britain to restrict in-work benefits to EU migrants for up to four years if the number of incomers "are putting an excessive pressure on the proper functioning of its public services".
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However, member states would have to "gradually increase access to such benefits" the longer an EU migrant is in work.
Prime minister David Cameron has also won concessions on the payment of child benefit to workers whose offspring live abroad.
Under the Tusk proposals, those payments would be index linked to the cost of living in the country where they live.
The deal will also give member states greater powers to ban terror suspects “likely to represent a genuine and serious threat to the public".
It says: "Member states may take into account past conduct of the individual concerned and the threat may not always need to be imminent."
Cameron said the nine-page document "delivers substantial change", but it is unlikely to satisfy eurosceptics.
'RED CARD'
The paper also includes a proposal for a “red card” system to allow member states to block or amend measures from the European Commission.
Laws could be changed if 55% of national parliaments object to them.
A Number 10 source said: "This will strengthen the power of Westminster to stop unnecessary EU laws and addresses concerns that the current ‘yellow card’ system has not proved strong enough.
"It ensures that the European Commission cannot just ignore the will of national parliamentarians and delivers greater democratic control over what the EU does.
"As the prime minister has said, it it is national parliaments which are, and will remain, the true source of real democratic legitimacy and accountability in the EU and this breakthrough will ensure that national parliaments’ voices are heard loud and clear in Brussels."