A Birmingham Labour MP led calls yesterday for the Government to restrict the next wave of migration from the n ew European Union countries.
Gisela Stuart (Edgbaston) joined opposition Tories and campaign groups in saying Britain would suffer in the long term if migration from Romania and Bulgaria was allowed to go unchecked.
"I don't believe we should open our borders completely," she said.
"You could understand the thinking with Poland. It was a country at the heart of Europe which was coming home. It's not the same with Romania and Bulgaria.
"It's also bad for the countries people are coming from if their brightest young people are all moving to Britain."
Tory MEP Philip Bradbourn said: "We should have followed the rest of the EU in having a transition period when new nations joined in 2004.
"We need a sensible transition period for Romania and Bulgaria. It does not mean stopping people coming in, but in common with the rest of Europe we want to do it in a measured way."
Figures published by the Home Office revealed 427,000 Eastern Europeans have come to work in Britain since the expansion of the European Union.
This does not include self-employed workers - thought to cover a significant number of Eastern Europeans in the building trade.
The Midlands was home to more Eastern Europeans than any region except London and the South-east.
Conservatives echoed the call for stricter controls. Damian Green, the shadow Immigration Minister, said: "It is vital that we learn the lessons of the unprecedented numbers who came into this country after the last expansion of the EU.
"The Government should impose conditions similar to those applied by most European countries to the last wave of EU accession countries."
But the financial benefits of immigration were highlighted by business leaders and the Institute of Public Policy Research, a left-wing think tank.
CBI director-general Richard Lambert said: "The UK has benefited greatly from the hard work of migrants from new accession countries, such as Poland and Lithuania.
"They have helped with skills shortages across the economy, particularly in the construction and hospitality sectors."
Danny Sriskandarajah, of the Institute of Public Policy Research, said: "We shouldn't resent these young workers wanting to come to the UK to pluck chickens, pack boxes or pick fruit."
Ministers have hinted they may impose restrictions this time, but no decision has been made.
Home Office Minister Tony McNulty said: "We are yet to take a decision as to what access Bulgarian and Romanian nationals will have to our labour market."
Senior Labour backbenchers added to the pressure on the Government last night.
Former Home Office Minister John Denham, who also chairs the Commons Home Affairs Select Committee, said the UK needed "breathing space" before accepting new immigrants.
Another Labour former Minister, Frank Field, has called on the Government to restrict the right of Romanians and Bulgarians to work here until an EU-wide policy came into force.