The talks with European Commission chief Jean-Claude Juncker are set to focus on an emergency "migration brake" that would meet Cameron`s controversial key demand -- a four-year limit before European Union workers in Britain can claim welfare payments.

A deal would pave the way for EU President Donald Tusk to make formal proposals on Monday, in time to reach an agreement with the other 27 EU leaders at a crucial summit on February 18-19.

If Cameron gets a deal at the summit he is then expected to hold an in-out referendum in June on Britain`s four-decade old membership of the EU, with his own position in the balance.

These negotiations to prevent a so-called "Brexit" which would make it the first country to leave the EU, come amid a series of crises for the bloc including the biggest influx of migrants and refugees to Europe since World War II.

In Britain, a eurosceptic former minister in Cameron`s centre-right Conservative party described the migration brake proposal as an "insult".

"That proposal is an insult to the United Kingdom. It`s not a serious offer," John Redwood told BBC radio.

"We need to take back control of our borders and we need to be able to control our own welfare system. That falls well short of that."

- Proposals likely Monday -

In a sign of the urgency of the talks, Cameron cancelled a visit to Denmark and Sweden to hold Friday`s working lunch with Juncker, the head of the EU`s powerful executive, whose appointment Cameron opposed in 2014.

He will also host a hastily-arranged dinner with Tusk in London on Sunday night, followed by a meeting with German Chancellor Angela Merkel in Hamburg on February 12.

Tusk is likely to table his proposals on Monday, European sources told AFP.

Cameron has set out four key areas for a deal: migrant benefits, safeguards against more political integration in the EU, protection of countries that do not use the euro currency -- a key issue for the City of London financial district -- and the boosting of economic competitiveness.

While Brussels officials say most are achievable, the major sticking point has been Cameron`s insistence that EU migrants employed in Britain must wait four years before claiming welfare payments such as tax credits or housing benefits.

A "migration brake" that would allow Britain or any other country to limit benefits to EU migrants, if it can show its welfare system is under strain, is one of the options that the EU is examining, diplomatic sources have told AFP.

There is widespread opposition to a benefits limit among the other 27 EU nations, particularly in central Europe, which says the move would be discriminatory and harm the bloc`s core principle of freedom of movement.

Britain says the move will cut immigration in a country that looks set to be the EU`s most populous by 2050.

Referendum in June?

Asked about the "brake" plan, Cameron said on Thursday: "I`m glad that others in Europe are now taking on board this issue and looking at strong alternatives to the proposal I put forward."

Cameron set out his reform demands to other EU leaders at a summit in December in which senior European officials said he had made a convincing case, overcoming last-minute objections by a handful of countries.

France has however appeared sceptical in recent weeks, with Prime Minister Manuel Valls warning at the Davos forum last week that a deal was unlikely at the February summit.

Cameron has insisted that he is in "no hurry" for a deal and will walk away if he does not get want he wants.

The next EU summit is in March but British officials have said that is likely to be too late to allow preparations for a referendum in June, which is believed to be Cameron`s preferred date.

Cameron has openly said that he will have the vote before the end of 2017, but the longer he waits the more he is at the mercy of events in a bloc threatened by an unprecedented migration crisis, and by rifts in his own party over Europe.

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