LONDON (AFP) - European immigrants to Britain paid more in taxes than they received in benefits over the last decade, according to research published on Wednesday amid a heated debate over EU migration.

The report, which found that EU migrants contributed a net £20 billion (S$41.3 billion) to the public purse between 2001 and 2011, comes during rising political pressure over immigration.

British Prime Minister David Cameron has proposed capping numbers of low-skilled migrants from Europe as he tries to counter the mounting challenge from the anti-EU UK Independence Party ahead of a May election.

The proposal has caused friction with Brussels and other European governments.

The academics at University College London found that migrants from the eastern European countries that joined the EU in 2004 - often singled out by anti-immigration groups as a drain on the exchequer - made a net fiscal contribution of about £5 billion in the decade to 2011.

Immigrants from the original 15 members of the EU contributed £15 billion.

In comparison, British-born workers made a negative contribution of £591 billion, and immigrants from outside the EU were a net cost of £118 billion.

"A key concern in the public debate on migration is whether immigrants contribute their fair share to the tax and welfare systems," said study co-author and UCL professor Christian Dustmann.

"Our new analysis draws a positive picture of the overall fiscal contribution made by recent immigrant cohorts, particularly of immigrants arriving from the EU."

The European migrants contributed more to the public purse than they took out because they were more likely to work than British-born people and received less state welfare, the study said.

"European immigrants, particularly, both from the new accession countries and the rest of the European Union, make the most substantial contributions," Professor Dustmann added.

The chairman of immigration group MigrationWatch UK Andrew Green played down the report, saying it confirmed that immigration overall was a net cost to Britain over the last 17 years.

"As for recent European migrants, even on their own figures, which we dispute, their contribution to the exchequer amounts to less than £1 a week per head of our population," Mr Green said.

German Chancellor Angela Merkel reportedly warned Cameron this week that he was approaching the "point of no return" with proposals to restrict immigration.

A spokesman for Ms Merkel said that free movement of people in the EU was "not negotiable" for Germany.

Mr Cameron has vowed to renegotiate the terms of Britain's membership of the bloc, before holding a referendum in 2017 on whether to leave, if he is re-elected in six month's time.