Migrants flooding into Britain bring only 4p a week in financial benefit to each person living here, a report has revealed.

But the economies they have left behind are receiving an enormous boost as workers send home to their families more than £10m every day.

The analysis by Migrationwatch explodes the Government's claim that huge levels of immigration have had an overwhelmingly positive impact on the economy.

The benefit is, in fact, only 'very slight'. It amounts to only £2.10 a year - or £126m - for each of the 60m people living in the UK, and would buy only a third of a Mars bar each month. At the same time, according to the Government's own research, migrants send home up to £4 billion in remittances every year - money effectively lost to the UK economy.

Sir Andrew Green, Migrationwatch chairman, said: 'Of course many immigrants make a useful contribution to the economy but taken in total the economic benefit is at best marginal.

'The main beneficiaries are the immigrants themselves who are able to send home about £10 million a day, not the host nation.'

The Government, desperate to justify the unprecedented influx of migrants since Labour came to power, boast they boost the country's Gross Domestic Product by £4 billion a year.

But Ministers fail to point out that, in order to achieve this, huge numbers of new arrivals - around 185,000 each year - are being added to the workforce.

Once the increase in the population is taken into account, the overall impact of migration is to benefit GDP by only 0.1 per cent, or 4p a week for each person living here.

Sir Andrew, whose group analysed a series of reports on the benefits of migration, added: 'Of course many immigrants make a useful contribution to the economy but taken in total the economic benefit is at best marginal.

'The main beneficiaries are the immigrants themselves who are able to send home about £10 million a day, not the host nation.'

Sir Andrew said the benefits of immigration include keeping inflation, and therefore wages, low - factors widely credited for Gordon Brow's relative economic success.

But he added this was not good news for British workers, who are finding their pay packets squeezed.

The Treasury has never admitted keeping down inflation is a positive consequence of the huge influx of migrants.

Critics say this reluctance stems from not wanting to admit migrants are pegging the wages of Labour's core working-class support.

Yesterday, this sparked a dire warning from a Labour leadership contender Jon Cruddas that - unless the party addresses the issue - it could play into the hands of the BNP.

Hourly wages for roofers in London have been slashed by £2.50 an hour in the past six months, he said.

It follows the arrival of 600,000 eastern Europeans over the past two years - with tens of thousands of Romanians and Bulgarians expected to follow them over coming months after being granted full Mr Cruddas, who is from the left-wing of the party, said: 'We are playing for really high stakes.

We need to prove that we understand the very real tensions in these communities.

'This is an extreme demographic change moving at a velocity we have never seen in our lifetime.'

The Home Office made a staunch defence of the economic impact of migration. A spokesman said: 'The Treasury estimates that migration accounts for 10-15% of trend growth, and independent research has found that migrants make a net contribution to the Exchequer.

'In the last few years we have seen a large movement of people from the EU coming here to work.

'There is a clear consensus from commentators, business and our own research that this has helped the economy to grow. There is no evidence that it has increased unemployment.'

The CBI's Susan Anderson said: 'Migrants to the UK bring valuable skills and ideas with them and help to fill job vacancies where Britons are unable or unwilling to do so.

'Their taxes help pay for our public services and our pensions, long after many migrants have returned home. Their presence also helps keep inflation low at a time when there are many forces pushing the other way.'

But Shadow Home Secretary, David Davis, said: 'The figures in the Migrationwatch report contrast sharply with what the Government claim and betray a chronic deficit of information on immigration.

"Immigration can be a real benefit to the country but only if it is properly controlled. In order to control immigration you need to have accurate information about its level and effects.

"The Government patently has neither. Ministers need to stop sticking their heads in the sand and start facing up to this issue so that it can be of benefit to the country.'