A million more people will be employed in Britain by 2020 but most will be workers from abroad 

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Tory committee member Mark Garnier accused the Government of ‘confusion’ over its immigration policy – that it claims to want to reduce arrivals while relying on them to power the economy

Migrants will make up the largest share of the rise in people in work during this Parliament, according to Treasury watchdogs.

The Office for Budget Responsibility (OBR) expects numbers working to jump by 1.1million to a record 32.2million by 2020.

Robert Chote, OBR chairman, told the Treasury Select Committee yesterday: ‘About three-quarters of that [increase in employment] would arise from migration.’ 

That equates to an 825,000 surge in migrants working, from now to 2020.

It will fuel claims that ministers need mass migration to balance the books. 

Tory committee member Mark Garnier accused the Government of ‘confusion’ over its immigration policy – that it claims to want to reduce arrivals while relying on them to power the economy. 

Mr Garnier, yesterday said: ‘Around 800,000 is a huge a number of migrants we need to rely on to meet the economic forecasts of this country. People will be surprised by that whatever their views on immigration. It is an awful lot.

‘Migrants do bring benefits. But if you look at the policy of cutting net migration on the one hand and requiring these numbers of migrants to meet our economic forecasts on the other, there is confusion about this.’ 

David Cameron has pledged to cut annual net migration to ‘tens of thousands’.

But according to the Office for National Statistics, net migration will total more than 1.1million up to 2019-20. The population is tipped to rise by nearly 2.3million to around 67.4million in that time.

Mr Chote told MPs that based on these figures, migration accounts for around ‘half’ the rise in population – but three-quarters of the rise in employment because newcomers ‘tend to be of working age’.

Extra jobs will boost growth, helping Chancellor George Osborne, whose Autumn Statement outlined plans for a surplus of £10.1billion in 2019-20.

David Cameron has pledged to cut annual net migration to ‘tens of thousands’. But according to the Office for National Statistics, net migration will total more than 1.1million up to 2019-20

Mr Osborne and leadership rival Theresa May are tussling over new controls on foreign students. Nick Timothy, who worked for Home Secretary Mrs May, said the Government ‘is no longer trying’ to cut record migration. 

Experts claim if migration fell to below 180,000 a year, from around 330,000 last year, Mr Osborne would miss his target for getting Britain back in the black. 

his target for getting Britain back into the black by the end of this Parliament.

Lord Green, chairman of MigrationWatch, said: ‘This is important evidence that many of the additional jobs being created are in fact going to immigrants.

‘This adds to the size of our economy and pleases the Treasury but it also makes Britain much more crowded.

‘The only solution to that is to get immigration under control not to attract yet more immigrants.’