The Chartered Institute of Personnel and Development (CIPD) has called for an independent investigation into the costs and benefits of immigration for the UK.
The move comes off the back of new government statistics which show that about 447,000 people have moved to the UK from the 10 countries that joined the European Union in 2004.
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.
John Philpott, chief economist at the CIPD, said the only way to restore public confidence in immigration levels was a clear restatement of government policy on mass economic migration, alongside a thorough independent assessment of all the costs and benefits.
“On balance, the benefits [of immigration] have outweighed the cost, mainly because a bigger pool of foreign labour has helped keep wage inflation in check and enabled a faster rate of economic growth than would otherwise have been achieved,” he said.
“CIPD research shows that a third of UK organisations employ workers from EC accession countries. Many [employers] point to their willingness to work as well as their skill levels as key reasons for hiring them.
“Though the CIPD remains concerned about mitigating the costs – for example, by means of improved education and welfare, to work measures for ‘home-grown’ jobless people – it is not immediately obvious that restrictions should be placed on further migration from the new EU countries, particularly if, as expected, Bulgaria and Romania join the EU next year,” Philpott added.
“If restrictions on migrants are deemed necessary for labour market or other reasons these should be imposed on less skilled migrants from outside the EU, which would demonstrate that the UK remains at the forefront of promoting the wider economic objective of a single European labour market and increased labour mobility within the EU, matching that found in the United States,” he said.
The Conservatives have called for restrictions on immigrant workers from Bulgaria and Romania.
Trade and industry secretary Alistair Darling responded by saying migration would be "properly managed".