By Kylie MacLellan

LONDON (Reuters) – British Prime Minister David Cameron’s pledge to cut net immigration to below 100,000 a year was undermined on Thursday by figures showing that a net 212,000 people moved to Britain in the year to September, a jump of 37 percent.

With polls regularly showing immigration to be one of voters’ top three concerns, Cameron is under pressure ahead of European elections in May and a national election next year to make good on his promise to cut the net influx to the “tens of thousands” by 2015.

Eurosceptic lawmakers in his Conservative party, trailing in the polls, want him to get tougher, partly to dissuade its supporters from defecting to the anti-EU UK Independence Party (UKIP), which opposes “open-door immigration”.

The Office for National Statistics (ONS) said on Thursday that the net flow of long-term migrants into Britain was up from 154,000 in the year to September 2012.

The number of EU nationals who came to Britain increased by 40 percent to 209,000, it said, the highest estimate since the figures began in 1964. EU citizens all have the right to live and work in each other’s countries, with some temporary exceptions for new member states.

Net migration of EU citizens more than doubled, the ONS said, with the number of Romanians and Bulgarians rising sharply ahead of the removal of restrictions on their right to work in Britain on January1, 2014.

A spokesman for Cameron said there had been a significant fall in net migration since its peak in 2010 and the government was sticking to its target.

“That is absolutely our objective and that is what we are going to continue to work towards,” he said.

This month the government laid out new rules designed to limit the access that migrants from other European Union states have to Britain’s welfare system.

It has also said Britain will stop helping jobless immigrants with their housing costs from April, and has brought in new rules to prevent EU migrants claiming welfare benefits as soon as they arrive.

The main opposition Labour party said Thursday’s figures showed government policy was “a mess”.

UKIP leader Nigel Farage said it was “utterly pointless setting immigration targets when you can’t even decide who comes in to this country”.

“Until we end the open-door immigration policy with the EU and take back full control over our borders nothing can really be done,” he said.

(Additional reporting by William James; Editing by Andrew Osborn and Kevin Liffey)

• Politics & Government
• Immigration Issues
• Prime Minister David Cameron