Why are there holiday delay warnings over the EU's new border system?

There have been warnings of queues at airports in Europe this summer because of the EU's new digital border control system.

It is the first summer peak period since the Entry/Exit System, or "EES", came in.

It requires UK travellers to register fingerprints and a photo alongside a passport scan.

It tracks who enters and leaves the Schengen free movement zone, which covers 29 European countries , external.

"Third country" nationals - including UK citizens - must provide fingerprints and a photo at passport control.

Brits flying out to a number of popular holiday destinations including France, Spain, Portugal and Italy will be required to do this at automated kiosks after they land.

Some passengers, including children under 12, have their passport checked by border staff instead.

EES started to be rolled out in October last year and is now fully up and running.

The time it takes to register biometric information means people have been told to prepare for a wait at border controls.

During the introductory period, queues started to flare up at certain airports at busy times.

Since then, the system has been working well in some airports, while waits of several hours have been reported at others.

A representative of airline trade body IATA has warned queues in some places could be as long as six hours.