The UK's privacy watchdog has raised concerns over the use of fingerprinting for passengers at Heathrow's Terminal 5 (T5).

Airport operator BAA plans to take four biometric fingerprint records and a digital photograph of every passenger who passes through the £4.3bn terminal - which opens on Thursday (27 March).

The plan aims to improve security by ensuring that the person boarding at the gate is the same person who checked in and passed through security checks - a function needed because international and domestic travellers will both use the same airside facilities.

But a spokesman for the Information Commissioner's Office said the watchdog was still looking at the privacy implications of the system.

"We have concerns about the routine collection of fingerprint information from passengers and we will require reassurance from BAA that the data protection implications of the proposals have been fully addressed," she said.

"We will be weighing up the security benefits of the scheme against the impact on privacy and asking what other less intrusive alternatives have been considered."

A similar system already operates in most international airports in the US, though other UK international airports rely on photographs and not fingerprints to perform the same checks.

BAA said all data will be encrypted immediately and destroyed within 24 hours, after the passenger has passed through the system.