A report by the London Skills Forecasting Unit found that many young people lack any experience of computers, while many workers were unwilling to improve their IT skills.

Of 14,000 Londoners surveyed, 43% of the unemployed had no computer skills, as opposed to 22% of those in work.

The most worrying statistic from the report was that 20% of people aged 16 to 24 have no knowledge of computers.

'Tackle issue'

Director of the London Training and Enterprise Council, Judith Rutherford, said: "While our survey covers London there is no doubt this is a national problem, and the threat of an IT underclass in Britain is a very real danger which government, employers and individuals ignore at their peril.

"If more people do not become IT-literate they will be excluded, or highly restricted, from taking a wide range of jobs. London needs concerted effort to tackle this issue.

"We all have responsibility for our own development and, if the right training is not available at work, people should look to improve their IT skills through courses run at local colleges or on the Internet."

The survey is part of a Lifelong Learning in London report, which also showed that more than 30% of the workforce did not receive any job-related training last year.