Weaknesses in a £1.2bn computer system to track journeys into the UK could allow undesirable individuals to slip into the country, a security expert has claimed.
From 2010 the e-Borders system will cross reference the personal details for almost all passengers travelling to and from Britain against a watchlist of suspects.
In a report for the Institute for Public Policy Research, Frank Gregory, professor of European Security at the University of Southampton, warned that it will be possible to fool the system.
The report said: "There are two key problems with the e-Borders programme. First, it will not reveal if the person matching the identity documents has created a false identity and, second, 'watchlist' scrutiny only works if a suspect person continues to use a 'flagged' name."
The rollout of e-Borders will start next month, with the system used to cross reference the names and other details of passengers travelling to British airports, rail and ferry terminals.
Project Semaphore, a prototype to test the e-Borders system, logged details of passengers travelling from a handful of UK airports from 2004 to 2008, and recorded more than 79 million passenger movements.
A UK Border Agency spokesman said the approach of checking passenger details before they travel to Britain had already proved its worth.
"The UK Border Agency has a network of immigration liaison officers working closely with airlines and intelligence organisations overseas — they are based at airports and ensure that those travelling on high-risk routes are who they claim to be," he said.
"Over the last five years [2003-2007 inclusive], our airline liaison officers have prevented nearly 210,000 people boarding planes without proper documents — that's around two jumbo jets every week."
The British Air Transport Association (Bata), the trade body for UK airlines, recently warned that the system could cause disruption to holiday travellers when it is introduced.
