He said the first requirement for joining the visa-waiver programme, which allows visa-free entry for up to 90 days for tourists, was a rejection rate of 2 per cent, 'which Hong Kong is not yet at'.

Justice Department approval was also required.

'It doesn't appear at this time that any country is going to be added any time soon to the visa-waiver programme,' he said.

The programme includes most European countries as well as Australia and New Zealand.

In the wake of the September 11 terrorist attacks, the Patriot Act introduced a requirement for machine-readable passports for member countries, which also have to offer reciprocal visa-free entry for US citizens and satisfy security concerns.

Mr Brizzee said that even for qualified countries, students, exchange travellers and business visitors still needed visas.

He was speaking during a meet-the-media session for US Department of Homeland Security official Robert Mocny, who attended the third Asia-Pacific discussion forum on electronic identity documents that ended yesterday.

Mr Mocny, a deputy director of the US-VISIT Program of the department's Transportation Safety Administration, said 115 airports and 15 sea ports had implemented US-VISIT procedures, which include taking digital fingerprints.

The programme - which sparked a visa row between the US and China after Beijing objected to its citizens being fingerprinted - has been in place since January 15.

'The procedures are now regarded as a top priority for the US Department of Homeland Security as they enhance security for US citizens and visitors while facilitating legitimate travel and trade across our borders,' Mr Mocny said.

Unique biological features - such as fingerprints and retinal images - are likely to be incorporated into Hong Kong passports from 2007.

The number of US visas issued in Hong Kong jumped to 50,000 in 2003/04 from 42,000 in 2002/03.