About 447,000 people have come to the UK from the 10 countries that joined the European Union in 2004, according to new government figures.
The government originally predicted the accession would lead to 15,000 immigrants a year coming to the UK. The UK was one of only three EU member states that did not impose employment restrictions.
The figures are likely to fuel debate about whether the numbers should be limited when Bulgaria and Romania join the EU.
The Conservatives have called for restrictions on immigrant workers from the two countries, which are due to join in 2007.
Trade and industry secretary Alistair Darling responded by saying migration would be “properly managed”.
But Colin Yeo, a senior lawyer with the Immigration Advisory Service charity, said there was “a very strong economic case to allow people in”.
“I don’t see that many people from Britain are really wanting to work as fish filleters, meat-bone breakers, sandwich makers – the kind of low-paid jobs that really are absolutely essential to the economy and employers just aren’t able to recruit for,” he told BBC News.