British Prime Minister David Cameron has promised to end the draw that Britain's generous welfare system has on European migrants as part of his renegotiation of the country's deal with the EU.

He said 40% of EU migrants coming to Britain were helped by claiming benefits with the average claim of stg£6,000 (€8,437) per family.

And he said the new figures showed that it was time for Britain to reduce the taxpayer subsidies to stem the flow of EU migrants placing too great pressures on the country.

In a speech in London, in which he set out his wish list of four EU reform demands, Mr Cameron said the way to lessen the number of EU citizens coming to the UK was "by reducing the draw that our welfare system exerts across Europe".

He insisted he would deliver Conservative manifesto pledges to curb the number of European citizens coming to Europe by welfare reform - including banning EU citizens from claiming in-work benefits for the first four years.

His pledge on tackling the Freedom of Movement rules one of four objectives he has set out in a letter to the European Council President Donald Tusk.

It is this objective which is the most controversial, since other EU leaders, including Germany's Angela Merkel, regard it as breaching the principle of free movement of labour across the EU.

Mr Cameron's four objectives are:

• Protecting the single market for Britain and others outside the Eurozone
• Writing competitiveness into the DNA of the whole European Union
• Exempting Britain from an "ever closer union" with a legally binding and irreversible agreement with other EU states
• Tackling abuses of the right to free movement, and enabling Britain to control migration from the EU

Mr Cameron demanded a legally binding, irreversible agreement with other EU states that would exempt Britain from "ever close union" and called for groups of national parliaments to come together to block the EU.

He said that Europe should have the "flexibility of a network not the rigidity of a bloc".

And for the first time, Mr Cameron tied Britain's role in Europe to national security saying: "Membership of the EU is a matter of national security too".

He said there would be no second referendum and that this was a once in a generation decision for the British people. He said: "If we vote to leave, we will leave".

And he told the EU: "This is our only chance to get it right".

In an attempt to head off criticism, the Prime Minister said: "There will be those who say - here and elsewhere in the EU - that we are embarked on mission impossible. I say: why?".

"I do not deny that seeking changes which require the agreement of 27 other democracies, all with their own concerns, is a big task. But an impossible one? I do not believe so for a minute".

His attempts to win reforms ahead of an in-out referendum on Britain's EU membership will come under attack almost immediately in the House of Commons.

After Europe Minister David Lidington makes a statement to MPs, eurosceptic Tory backbenchers will claim Britain cannot get a better deal in Europe without changes to treaties.