Amadeus, an IT system used widely in the air industry, crashed and was down for three hours yesterday afternoon.
British Airways was one of the airlines affected, and said that it experienced problem with its website for about three hours between 14:00GMT and 17:00GMT on Monday 30 January due to a "technical problem" at Amadeus.
Amadeus has also confirmed that "some of its customers" had experienced system issues, which affected users' ability to process passenger boarding information. Some travel agencies also experienced problems using the booking system.
The company said it is carrying out a full investigation into the cause of the problem, but has today said that the cause of the problem "appears to be a network component".
"We are continuing to investigate this in detail," it added.
Meanwhile, travel agency Thomas Cook has said that while its systems, provided by Galileo, were unaffected, airlines that load their stock onto Amadeus as their only global distribution system (GDS) "may have been affected".
In 2010, Virgin's Australian airline brand, Virgin Blue, experienced a large system outage caused by a failure on servers hosted by IT supplier Navitaire, that ran its reservations and check-in system.
Thousands of passengers were left stranded as a result of the 21-hour outage.