Amadeus, a company based in Spain that provides software to airports, airlines and the tourism industry, confirmed Thursday that a network issue temporarily caused disruption to some of its systems and services.
It later said its technical teams solved the problem and its systems were functioning normally again.
Amadeus would not say how many airlines or airports were affected.
London's Heathrow airport said a small number of airlines experienced 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.