The Government faced charges of incompetence after it admitted that 300,000 more foreigners were working in Britain than it had believed.
It was forced to apologise after it dramatically revised the number of overseas nationals taking up jobs in this country since 1997 from 800,000 to 1.1 million.
With immigration moving swiftly back up the political agenda, David Cameron promised a heavy cut to the levels of migration because of the " unsustainable" pressure it was placing on services.
Liam Byrne, the Immigration Minister, will today try to regain the initiative on the issue by announcing that tough restrictions on Romanians and Bulgarians working in the UK will remain in place for another year.
The Government's revised figures mean that foreign nationals account for up to 8 per cent of the workforce and have filled 40 per cent of the new jobs created over the last 10 years.
Mr Byrne said the admission proved the immigration system needed to be overhauled, with the reintroduction of checks on people entering and leaving Britain.
"It's always frustrating when new information like this emerges," he told the BBC. "But it underlines why it was a mistake to remove exit controls and why we urgently need new systems in place to count people in and ...out of the country."
But Chris Grayling, the shadow Work and Pensions Secretary, said: "This confirms fears that ministers have simply lost control of our systems for migrant workers. It really does call into question the competence of Ministers and of the Government as a whole."
Earlier, in his first major speech on immigration, Mr Cameron called for annual limits on numbers of incomers as he set out a "modern Conservative population strategy" to slow Britain's population growth, which is estimated to pass 70 million within 25 years.
He refused to specify a figure for the optimum levels of net migration from outside the European Union, although he made clear it would be substantially less than the current 190,000 a year.
The Tory leader called for the minimum age for spouses moving to Britain to be raised from 18 to 21 and for them to be required to speak English.
He promised a Tory government would set up a Border Police Force with powers to track down and remove illegal migrants.
"Of course, we should recognise that in an advanced, open economy there will be high levels of both emigration and immigration. But what matters is the net figure, which I believe is currently too high ...It is time for change. We need policy to reduce the level of net immigration."
The Home Office will confirm today that the strict restrictions on the lower-skilled placed on Romanians and Bulgarians working in Britain when the two countries joined the European Union in January will be retained.
Apart from the highly-skilled and self-employed, they have only been allowed to enter under seasonal schemes in agriculture and food-processing. Just over 6,000 worked in Britain under the schemes this year.
After a review of the policy, Mr Byrne has decided to retain the policy for fear of creating a "pull-factor" attracting Romanians and Bulgarians to this country.
The stance will dismay the Romanian and Bulgarian embassies which have protested that the UK government's hard line discriminates against their citizens. It will also disappoint employers who say they are suffering labour shortages that could be filled by people from the two east European states.Reuse content