India, Sept. 13 -- Ryanair has warned that passengers travelling through some of Europe's busiest airports face a renewed spell of long queues after a temporary flexibility allowing border staff to ease pressure from the EU's new biometric checks lapsed on 7 September, with the airline pressing Brussels for an emergency extension into next year.

The Entry/Exit System, or EES, has been fully operational at all Schengen external borders since 10 April, requiring most non-EU travellers, including British passport holders, to register fingerprints and a facial image the first time they cross into the 29-country zone.

The rollout has been marked by long queues, missed flights and mounting frustration from airlines and passengers since it wen...