Within a month 30 had been recaptured because of random biometric checks.

ECONOMIST: Biometric data and the Afghan war

Passengers vetted via background checks would have a biometric identifier, such as their fingerprint or iris pattern, in their passport or other travel document.

BBC: New measures in airport security

The UK will move towards an integrated electronic border security system, linking biometric passports and visas with electronic checks on entry and exit, helping to track and intercept terrorists and criminals and to stop illegal immigration.

BBC: Key points: Brown speech