More Polish came to the UK than expected

He was responding to Conservative calls for restrictions to be placed on workers from Bulgaria and Romania.

The two countries could join the EU as early as January 2007. Tory immigration spokesman Damian Green said the government should limit migrants.

However, Mr Darling said immigration would be "properly managed".

The target date for Bulgaria to join the EU is 1 January 2007 but this can be postponed by one year if the country is deemed to be unready.

There is a very sensible, moderate, practical case to make that we cannot simply have uncontrolled immigration from these new countries. Damien Green EU candidate countries Send us your comments See interview

The European Commission will issue a report on Bulgaria and Romania in the autumn, which will indicate whether there is to be a delay.

Mr Green said the government's "mistaken planning" when the EU expanded in 2004 had meant a migrant influx from countries such as Poland.

While the government had expected as few as 13,000 to come, more than 600,000 had arrived, according to Mr Green.

Mr Darling said: "What we need to do is balance the skills that we require - and yes, our economy does require skills in various areas - and at the same time having a system that is properly managed so we can take care of all the other things we need to consider, like the healthcare system, the education system and so on."

The UK government has yet to indicate whether workers from Romania and Bulgaria will enjoy the full working rights associated with being an EU citizen from the outset.

Other countries had imposed quotas on immigrants at the time of the 2004 expansion.

Mr Green, speaking on BBC News 24 Sunday, said: "What we are saying is that we should learn from the government's mistaken planning over Poland and the other countries and we should use the powers that are there in the [EU] treaty to regulate the flow, to control the flow of people coming from Bulgaria and Romania."

Pressure

Another influx could "put unacceptable pressure on public services, on school places, on the provision of housing, which causes big problems for certain local communities".

He said a leaked Home Office report had suggested 45,000 criminals could be considering entering the UK.

"That's one concern but even without the criminal element, there is a very sensible, moderate, practical case to make that we cannot simply have uncontrolled immigration from these new countries."