Their verdict was a huge embarrassment to Cabinet ministers, who have claimed most jobs went to Britons.

It brought new criticism for Gordon Brown and his promise of "British jobs for British workers".

The calculation of how many migrant workers there really are in Britain was made by the Statistics Commission, set up by Labour to check the integrity of official figures.

It had been called in by Labour MP Frank Field during a row in October, when ministers were forced to admit their own figures were too low.

The commission said 1.4million workers born abroad had taken jobs in Britain since 1997. That was 81 per cent of the 1.7million new jobs for people of working age.

The commission said it was counting all workers born abroad - rather than just foreign citizens, as Government officials do - because that produced a clearer picture of immigration.

Mr Field, the Birkenhead MP who was Tony Blair's first welfare reform minister, said last night: "We are even further from seeing British workers getting British jobs than we thought.

"The economy has been creating an unprecedented number of jobs and we have really keen people from abroad coming to do them. But often British workers are not getting a look-in."

Mr Field called on the Government to stop Eastern Europeans taking jobs here.

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Under Labour the majority of new jobs have gone to immigrants

He said: "We could have stopped Polish and other Eastern European workers coming when their countries joined the European Union. But we didn't, because the Home Office said there would be only 5,000 to 13,000 a year.

"The Government should now go to the European Commission and ask permission to stop workers from Eastern Europe.

"This is clearly damagingthe British labour market and British unemployed people are not moving into work."

Tories said the Prime Minister's promise to British workers had been shown to be empty. Shadow Home Secretary David Davis said: "So much for Gordon Brown's dubious, factually-inaccurate and potentially-illegal comment of British jobs for British workers.

"We now know that 80 per cent of these jobs were filled by people from abroad.

"When will Gordon Brown learn that uncontrolled immigration leads to uncontrollable pressures on public services, housing, schools and community relations?"

The Statistics Commission said estimates of the numbers of newly-employed migrant workers began at just over 50 per cent, if foreign citizens alone were counted.

The higher estimates cover all people born abroad, including those who had since become British citizens. It said: "Information about country-of birth would seem to be more relevant to questions about migration than information about nationality, which can change over time."

It said government departments should agree a common approach to avoid continuing confusion, adding: "We understand that discussions to this end are taking place".

The commission said that when all age groups were considered, including those over normal retirement age, migrants still took 68 per cent of 2.1million new jobs.

All the estimates are based on the Labour Force Survey, a large-scale poll carried out regularly by the Government's Office for National Statistics.

The row over the figures broke out when Work and Pensions Secretary Peter Hain said 800,000 foreign nationals had taken jobs in Britain since 1997.

Under fierce pressure he was forced to change the figure to 1.1million.

Home Secretary Jacqui Smith tried to defend Mr Hain by saying the majority of jobs had still gone to Britons - but she was rapidly proved wrong.

The Department of Work and Pensions insisted last night that the commission's findings showed it had got its figures right - at least at the second time of asking.

A spokesman said: "The commission has confirmed the revised estimates we issued in October are correct. Of the 2.1million increase in employment since 1997, about 1million were UK nationals and 1.1million foreign nationals.

"There have been, and remain, British jobs for British workers. Consistently there have been more than 600,000 job vacancies on any given day.

"This, allied to the fact that the number on key outofwork benefits has fallen by a million in the last decade, shows there are jobs there and that people are coming off benefits and getting to work."

The DWP did not explain how Miss Smith came to make her claim.