Hi-tech eye scanners, originally designed to reduce passport queues, have been scrapped at two of the four UK airports where they were in operation.

The scanners, introduced in 2005, have been mothballed at Manchester and Birmingham airports after critics said the Iris Recognition Immigration System (Iris) made airport delays worse.

The system will remain in place at Heathrow and Gatwick airports until after the summer's Olympic and Paralympic games.

The UK Border Agency said: "We are considering the future of Iris in the context of our broader approach to automation at the UK border."

On its website, the UK Border Agency said: "Iris is no longer available at Birmingham and Manchester airports."

Criticism of the technology surfaced five years ago when a study revealed that Iris had failed to meet half of the targets set for it.

Passengers complained that it took much longer than the 12 seconds estimated by the manufacturers to clear the gates.