Future EU countries could face new migration curbs

Promising to do an impact study on the issue, it added: “The possible need for and nature of transitional controls and/or a safeguard mechanism on the free movement of workers will be addressed in the course of accession negotiations on future enlargement”.

Under current rules, existing member states can impose “transitional controls” of up to seven years before people from new members enjoy full EU rights to come in search of jobs.

The UK says this is not enough to stop exceedingly large numbers moving from poorer countries in the east to the rich west.

Britain’s lifting of restrictions on Romania in January this year did not result in a large influx despite tabloid fear-mongering.

But prime minister David Cameron has come under strain on immigration due to gains by the eurosceptic Ukip party ahead of next year’s elections and ahead of a referendum on EU membership in 2017.

Writing in the Financial Times last November, he said one idea is to limit freedom of movement until new entrants attain “a certain income or economic output per head”. His second idea was to impose a “cap” if the number of migrants from a given country went beyond an agreed figure in a given year.

David Liddington, his Europe minister, on Wednesday welcomed the commission initiative, saying “I am pleased that the commission has taken it [Cameron's proposal] up”.

He also said it is proof that Britain's voice still counts in Brussels despite its referendum plans: “This is further evidence that we are working with partners to shape the debate about the future of Europe”.

The UK is one of the few advocates of further EU expansion among older member states.

It says that Turkey, a fast-growing Muslim country of 75 million people, should also one day join for “strategic” reasons.

A UK diplomat told this website the EU change is needed to “maintain confidence” in enlargement in the wider British public.

He noted that every EU state has a potential veto over individual steps in the enlargement process, such as the opening or closing of legislative “chapters” on labour in accession talks.