Academics at the London School of Economics have warned that the cost of an ID card is likely to be around £300, and could soar to as much as £500.

This compares to the figure of £93 given by the Home Office last month.

The LSE team is in the process of writing a new report, but said that the overall cost of implementation could rise to a staggering £19bn. This compares to the government's figure of £5.8bn.

This increase is due to the cost of integrating the card with other government computers, according to the LSE, such as those at the Home Office and Department of Work and Pensions, and in the NHS where the card is likely to be used to check eligibility.

The Home Office declined to comment.