One person was arrested by the London authorities as they continue to investigate the sale of unapproved aircraft parts that have been found in the fleets of major airlines.

According to the Associated Press, the arrest and seizure of materials took place during a raid in London, the U.K. Serious Fraud Offices said December 6.

The agency said that it had launched an investigation into fraud at AOG Technics Ltd., which has supplied aircraft businesses with parts for popular jet engines produced by CFM International for years.

Earlier in 2023, aviation authorities in the U.S., the U.K. and Europe warned businesses of AOG parts and asked companies to check the origin of components supplied by AOG.

Suspected unapproved engine parts have been found in airplanes belonging to American Airlines, United, Delta, Southwest, Ryanair, TAP Air Portugal and Virgin Australia.

In some cases, the parts are counterfeit, similar to knock-off handbags. In other instances, paperwork could have been forged, parts could have been mislabeled or used parts could have been passed off as new.