LONDON (AFP) - British Prime Minister David Cameron's promise to slash immigration suffered a blow on Thursday when official figures showed a surge in net migration, driven by new arrivals from within the European Union.
EU migration increased from 149,000 to 209,000 in the year to September 2013, contributing to an overall increase in net migration from 154,000 to 212,000, according to the Office for National Statistics (ONS).
The data is likely to fuel debate about the impact of Britain's membership of the European Union ahead of an in-out referendum that Mr Cameron has promised to hold in 2017, provided he is re-elected next year.
In particular, the figures will add to fears that Britain faces a flood of migrants from the EU's poorer members, with the number of Romanians and Bulgarians moving to Britain rising from 9,000 to 24,000 in a year.
This was even before official limits on the right of those countries' citizens to work in Britain were lifted on January 1 this year.
The ONS also recorded a large increase in migrants from the so-called EU 15 countries - those which joined before 2004 - from 23,000 to 65,000. This includes countries hit by the eurozone crisis, such as Greece, Spain, Ireland and Portugal.
Mr Cameron's centre-right Conservatives face a growing electoral threat from the anti-immigration, anti-EU UK Independence Party.
His government had vowed to cut net migration from hundreds of thousands to tens of thousands by the 2015 election, but this target now looks highly unlikely.
It has clamped down on migration from non-EU countries, and the new figures show this fell from 269,000 to 244,000 in the year ending in September 2013.
But Mr Cameron can do little about the new EU arrivals, a fact that some British eurosceptics have used as an argument for leaving the bloc altogether.
Of the 24,000 Romanians and Bulgarians who arrived in Britain in the year to September, an estimated 70 per cent arrived for work and 30 percent for study, the ONS said.
Overall, the number of EU citizens arriving to work increased by 40,000 on the previous year.
Mr Cameron has called for limits on freedom of movement from poorer EU states to the rest of the bloc, to avoid "vast migrations" caused by income disparity.