Interpol has confirmed at least two passports used by passengers on board the missing Malaysia Airlines flight were registered in its Stolen and Lost Travel Documents database, according to a statement released by the the France-based global police agency on Sunday.
The passports came from Austria and Italy and matched names to people who were not on the plane. Both documents were reported stolen from Thailand during separate incidents in 2012 and 2013.
Interpol said it is working with the National Central Bureaus to uncover the true identities of the passengers.
No checks on the documents were made from the time the thefts were reported to Interpol and their use on Saturday’s flight. The agency could not confirm if the stolen passports had been used previously to cross borders.
“Whilst it is too soon to speculate about any connection between these stolen passports and the missing plane, it is clearly of great concern that any passenger was able to board an international flight using a stolen passport listed in Interpol’s databases,” Interpol Secretary General Ronald K. Noble said in the statement.
Interpol also noted that only “a handful of countries” take precautions to ensure passengers are not able to board international flights with stolen passports.
The agency says only a few member countries systematically use its database for checking whether a passport was reported as lost or stolen in the system.
Interpol’s database contains more than 40 million travel documents and is searched more than 800 million times a year.
The U.S. conducts more than 250 million database searches annually, while the United Kingdom and the United Arab Emirates account for more than 120 million and 50 million searches respectively.