The previous estimate of £12.8 billion per year of the cost of immigration to Britain has been underestimated by £4 billion, which is the total amount sent out of Britain in each year by immigrants.

According to a new report titled “The Invisible Cost of Immigration” published by independent think tank Migrationwatch, immigrants are sending home a record £4 billion a year. This figure has doubled over the last decade and constitutes almost £11 million a day.

This is all money lost to the British economy, and is nearly two thirds the amount that the Government spends on its lavish foreign aid budget. According to Migrationwatch, the £4 billion is “likely to be an underestimate as it does not include money sent from the UK by unofficial banking channels.”

The new figures show that the economic ‘benefits’ claimed by supporters of record immigration levels are “at best illusory.”

Last year the House of Lords Select Committee on Economic Affairs found “no evidence” that net immigration generates significant economic benefits for the existing UK population. The Government’s own evidence showed that the benefit of immigration is marginal – annual extra production equivalent to just 62p per head a week.

In addition, a marked surge in remittances to Pakistan has shown that the number of illegal invaders in Britain from that region could be as high as 200,000.

This figure has been calculated by comparing official statistics on the number of Pakistani born workers in Britain with the increased level of remittances being sent to that country.

An examination of workers’ remittances shows that they are now more than six times higher than in 2001 but, according to the Government’s Labour Force Survey, the number of Pakistani born workers in Britain has risen by only 67 percent.

In 2001 about 108,000 Pakistani born workers remitted $80m, or about $750 a head. Assuming that remittances per head have doubled since then as wages have increased and workers have moved up the ladder, the current flow of $520m a year would require about 350,000 workers to send home $1500 each year.

However, only 180,000 Pakistani born workers appear in the official Labour Force Survey so the remaining 170,000 workers needed to reach this level of remittances are likely to be working in Britain illegally. Illegal workers are likely to be paid less than those here legally, so there could well be, on this very rough calculation, as many as 200,000 Pakistanis working illegally in Britain, said Migrationwatch.

“We already know from investigations by newspapers that there are significant numbers of fraudulent students from Pakistan but not all will have come via this route,” said Sir Andrew Green, chairman of that organisation.

“As there are still no checks on departure, a proportion of those coming as visitors might well stay on after their visas expire. In the five years 2004-8 over half a million visas were issued in Pakistan, including nearly 60,000 student visas. Others could have arrived on the back of a truck.

“In our view the only plausible explanation for such a rapid increase in remittances from Pakistan is a sharp rise in the number of illegal immigrants sending money home. Not only are illegal workers undercutting the wages of British workers but, in the case of Pakistan, there are serious security aspects to an immigration system that has more holes than a Swiss cheese. This requires a root and branch review of the visa system for Pakistan,” he said.