The restrictions represent a shift from the unlimited access Britain gave citizens of the 10 countries that entered the bloc in 2004, a freedom that resulted in an influx of hundreds of thousands of eastern Europeans, mainly Poles. The government was under heavy political pressure not to allow such an unrestricted flow of workers again.
Britain's labor market will be opened gradually to citizens of the two new member nations, said Liam Byrne, a minister in the Home Office, which handles immigration issues.
Unskilled workers will be allowed to work only in the agriculture and food-processing sectors under existing immigration quotas in those areas, he said.
Skilled workers will enjoy no more access to British jobs than they have now, he said. They will need work permits unless they are self-employed, studying or qualify as a "highly skilled migrant," a special category for those with certain skills, Byrne said.
He said the restrictions would be reviewed within a year, with consideration given to the British labor market's needs, the impact of immigration from the countries that joined the EU in 2004 and the openness shown by other European nations to Romanians and Bulgarians.
Byrne said Britain strongly backed enlargement of the EU and believed the large migration after the 2004 expansion had helped boost the economy.
"But we need to make progress on our immigration reforms and understand the transitional impacts from the last round of accession before we take the next step," he said in a statement. "That is why we have decided to take a gradual approach this time round."