Plummeting numbers of people leaving the UK to live abroad and the influx of migrants from Eastern Europe led to a 21% increase in net migration last year, figures showed today.
The number of people coming to the UK for more than a year, less the number leaving, hit 239,000, the second highest annual figure on record and the fourth highest figure for any 12-month period since records began.
Analysts and campaigners said it would make it "more difficult than ever" for the Government to fulfil its pledge to cut net migration to the tens of thousands by 2015.
The Government has no control over those leaving the UK and long-term emigration fell from 427,000 in 2008 to 336,000 last year, estimates from the Office for National Statistics (ONS) showed.
Long-term immigration remained constant overall at about 575,000, but the number of Poles and other eastern Europeans coming to the UK continued to rise.
Net migration from the so-called A8 countries which joined the EU in May 2004 - Poland, the Czech Republic, Hungary, Slovakia, Slovenia, Estonia, Latvia and Lithuania - rose almost eight-fold last year to 39,000 from 5,000 in 2009, the ONS said.
The number of Poles living in the UK has risen from 75,000 in 2003 to 532,000 at the end of last year, other ONS figures showed.
Around two in three of all A8 citizens who have migrated to the UK have been Polish, with 449,888 Poles working in the UK between April and June this year, up 15% from January to March.
And more than four in five Poles aged 16 to 64 were employed, compared with just seven in 10 of the UK population as a whole, during the second quarter of 2011.
A record 241,000 migrants also settled permanently in the UK last year, largely because tens of thousands of asylum seekers whose cases were in a backlog were allowed to stay.
Immigration Minister Damian Green said the rise in net migration covered a period before the Government's immigration reforms were brought in.
"After almost two years of increasing net migration the figures stabilised in the last quarter," he said.
"This explains why the Government radically changed immigration policy, from our first months in office, to drive the numbers down with a limit on economic migration and changes to student visas to ensure we attract the brightest and best whilst tackling widespread abuse of the system."
The increase to 239,000 from 198,000 in 2009 was the second highest year-end figure since records began in 1991, behind 245,000 in December 2004, but it was down slightly from 242,000 in the 12-months to September 2010.
It was also the fourth highest figure for any 12-month period on record, behind 260,000 in the year ending June 2005, 245,000 in the year ending December 2004, and 242,000 in the year ending September 2010.
Study remained the most common reason for those coming to the UK, with three in four of the 228,000 who came to the UK for study coming from outside the EU.
But fewer than one in five people coming to the UK had a definite job, the lowest level in more than six years.
Meanwhile, the number of those leaving the UK for work-related reasons was also at its lowest for three years at 179,000, the ONS estimates showed.
Dr Carlos Vargas-Silva, a senior researcher at Oxford University's Migration Observatory, said the figures made the Government's efforts to reduce net migration "more difficult than ever".
The "steep rise" in net migration from Eastern Europe "raises the question of whether Government policies to cut net migration from outside the EU may be stimulating a demand for more EU workers," he said.
"The UK clearly remains an attractive destination for migrants from A8 countries.
"There is a demand for their labour, wages are still much higher than Poland or other A8 nations and there are now well established A8 communities and networks here to help new and returning EU migrants find a job and negotiate the complexities of life in a new country.
"This adds up to the likelihood that the UK's population of Eastern Europeans will continue to increase for some time."
But the lack of control over emigration means there will "always be fundamental uncertainty about whether any overall net migration target will be hit".
Chris Nicholson, chief executive of the CentreForum think-tank, added: "Rather than showing anything about whether immigration controls are too light or too lax, the figures simply show that a net migration target is silly."
Sir Andrew Green, chairman of the campaign group Migration Watch UK, said the figures "lay bare the legacy of the Labour government.
"The coalition Government will have to face down some vested interests if they are to get anywhere near their target of tens of thousands."
But shadow Home Office minister Shabana Mahmood said the figures showed the gulf between the Government's rhetoric on immigration and the official figures.