Airlines are losing €440 million a year due to fraud, according to a report.
The report - which surveyed 180 airlines across five continents - found that 79 per cent of airlines have experienced some form of fraud in the last 12 months. The average airline loses €2.2 million a year to fraud, with low-cost carriers being the hardest hit.
The types of fraud identified include counterfeit or stolen tickets, cargo theft, false baggage claims, frequent flyer abuse and bouncing cheques.
However, the report, done by Deloitte and the International Association of Airline Internal Auditors, noted the biggest losses come from credit card fraud.
More than a third of airlines have been hit by credit card fraud, which accounts for around 60 per cent of all external fraud-related losses, it said. Credit card fraud is costing airlines an average of €735,000 a year.
Low-cost carriers were found to have the highest credit card fraud losses, due in part to the high number of airline tickets they sell online.
The report said the average number of fraud cases for the low cost carriers was over 1,000 a year, compared with around 300 for the network carriers.
Brian Murphy of Deloitte Ireland said: "However, not all the fraud was external. The study found a rise in the level of frequent flyer abuse, with increasing numbers of employees diverting points to friends and family.
"Worryingly for customers, 20 per cent of airlines also admitted cases of internal abuse of passengers' personal details with 7 per cent saying employees had stolen the identities of the airline's passengers."