More than 24,000 immigrants in Central London have been left off official population figures, resulting in an £18 million shortfall in town hall funds, it has been claimed.

Westminster City Council is publishing research that suggests that 11,000 short-term migrants and 13,000 illegal migrants are living in the borough at any one time. Council chiefs are furious that latest figures compiled by the Office for National Statistics (ONS) reduced the number of immigrants in the borough by 15,500 and have demanded a recount.

Local councils are allocated money largely based on the number of residents they have but figures compiled by the ONS fail to pick up temporary and and illegal immigrants.

Colin Barrow, Deputy Leader of Westminster City Council, said: “We are now calling for the Government to hold its hands up, admit they have simply lost count, and act quickly to sort this mess out.

“At present the Government prefers to ignore these people, as they are too difficult for them to measure, rather than fund services to support them.”

The Tory-controlled council will call on the Government to address the shortfall this morning at a conference to be attended by MPs and at least 25 other councils facing similar problems.

The council commissioned three separate studies to determine the size of the problem. The researchers found that short-term immigrants were more likely to register for mobile phones or bank accounts than for national insurance numbers or a GP, making them much more difficult to trace. Most people in this group lived in crowded flats in high-rise buildings to save more money to send home.

Australians made up 13 per cent of this group, the French 8 per cent, Italians 6.5 per cent, Americans 5.7 per cent and Poles 5.4 per cent.

Scott Dickinson, associate director of SQW, the independent consultancy that carried out one of the studies, said the real number of short-term and illegal immigrants was likely to be higher.

On of the studies said that many Chinese immigrants had to live in cramped accommodation but they stayed in London to send money back to China. Illegal Chinese immigrants were often exploited by their Chinese employers and it took them several years to pay back the cost of coming to Britain, about £4,000.

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