A Home Office spokesman said e-Borders would count everyone, including UK nationals, entering and leaving the UK. It would also improve the UK's ability to identify and keep out undesirable visitors before they arrive at ports of entry.
According to the Office for National Statistics, UK residents left the country 69.3 million times, and foreign nationals arrived 32.9 million times in the year to July, meaning the system would have to cope with at least 100 million trips a year.
Airlines and other passenger carriers will submit passenger and vehicle details to the e-Borders system before departure. These will be checked against databases of visas, passports, police records and watch lists maintained by law enforcement agencies to detect and prevent known undesirables from embarking, or allow the authorities to meet them at the port.
The Home Office said it was unclear whether e-Borders would have access to data available to police under the Prüm Treaty, which allows European police forces to share personal data collected during investigations.
e-Borders will rely increasingly on biometrics, such as digitised fingerprint images, to link people, travel documents and identities.
The scheme is a joint venture by the Border and Immigration Agency, Customs, police and UK Visas.