The government has denied claims problems with new iris-recognition equipment will cause major delays at British airports.
The eye scanning technology has been introduced at a number of airports to allow passengers a fast track through immigration.
But Tory MP Ben Wallace claimed passengers faced major hold ups because of problems with the system.
He said an official report on trials of the technology showed it had failed half of its assessments.
Speaking on BBC Radio 4’s Today programme, Mr Wallace said: ‘The pilot failed half its assessments: it wasn’t available when it was needed at the right level; when the system crashed, it took over eight hours to fix.’
Mr Wallace said passengers would pay the price for the lack of ‘proper rigorous testing’.
He added: ‘Millions of people are going to arrive at Heathrow and wait in a queue because the system has crashed for over eight hours.’
The iris-recognition equipment is in use at Heathrow, Gatwick and Manchester airports and will soon be extended to Birmingham.
Passengers can pre-register a photograph of the iris of their eye, and then have their iris scanned on arrival at automated barriers in the immigration arrivals hall.
More than 50,000 people have signed up, with 150,000 people passing through the new-style security checks last year.
A Home Office spokesman said that the eye scanning system was working well at all the airports where it has been introduced and that passengers were not experiencing delays.
He added: ‘If Iris (Iris Recognition Immigration System) does experience problems, passengers are still able to use the usual passport control.
‘The UK is at the forefront of plans to use the latest technology in immigration controls and Iris is an example of success in this area.’