Regular overseas visitors arriving at UK airports could face an iris scan to prove their identity by the middle of next year.

The Home Office Immigration and Nationality Directorate (IND) is to install the Iris Recognition Immigration System (IRIS) at 10 UK sites.

The system follows a successful trial at London's Heathrow airport last year (Computing, 15 November 2001).

Non-UK passengers who regularly travel in and out of the country will be invited to voluntarily enrol for IRIS.

A photograph of the iris - the coloured part of the eye - will be taken at airports and at mobile centres and stored on a database.

'A sort of unit that will be taken to places like universities to enrol foreign students,' a Home Office spokesman told Computing.

The Home Office wants the system up and running by July 2004, although implementation work has not yet started.

Airports authority BAA was heavily involved with last year's trials but a spokeswoman said the government had made no contact.

While the technology is generally regarded as promising, biometrics experts also have doubts over the integrity of iris databases.

Markus Kuhn, lecturer at the University of Cambridge says iris-recognition looks among the best of biometric options available but he warned: 'You need to have multiple storage sites and trusted individuals that constantly check the authenticity of the stored data.'

David Cameron, MP for Witney and member of the Commons Home Affairs Committee said: 'The theory is a good one, but we have to make sure everyone is consulted.'

Fellow member Janet Dean, MP for Burton added: 'If the biometrics are there, I'd very much support additional measures to increase security and ensure that accurate identification is made of the people who are travelling.'

Additional reporting by Mark Samuels