An influx of nearly 620 000 migrants to the UK could be expected after Bulgaria and Romania entered the EU, the think tank Open Europe said.

The number of migrant workers that entered the British labour market after the EU accession of new countries in 2004 caused tensions, as more and more locals found themselves unable to get a job.

Official statistics show that nearly 427 000 Eastern European migrants registered for work with British employers, Sunday Times said. If the self-employed migrants were added to the account, the total was near 600 000.

Britain was unprepared for such a number of migrants, as the Cabinet expected net inflow of only 13 000 workers a year by the end of the decade, Sunday Times said.

British employers' organisations still argue whether migrant workers influx helped or hindered the country, Sunday Times said.