MADRID (AP) — Authorities say passengers at airports around the world have suffered some delays because of a problem with check-in systems.

The Spain-based company Amadeus, which provides software to airports, airlines and the tourism industry, confirmed Thursday that a network issue caused disruption to some of its systems and services.

It said its technical teams identified the cause of the problem and services were gradually being restored.

It would not say how many airlines or airports were affected.

London's Heathrow airport said a small number of airlines were experiencing intermittent issues with their check-in systems at airports around the world. It said there might be delays but that passengers would be able to check in.