European aviation regulators have determined that an obscure London-based company supplied bogus parts for repairs of jet engines that power many older-generation Airbus A320 and Boeing 737 planes.

Manufacturing partners General Electric and Safran have been assisting in the probe of allegedly faked certification documents and unapproved parts for CFM56 engines that were distributed by London-based AOG Technics, according to the companies, public regulatory filings and letters to operators viewed by Bloomberg.

"Numerous Authorised Release Certificates for parts supplied via AOG Technics have been forged,” the European Union Aviation Safety Agency said in a statement in response to Bloomberg queries. In each case, the organization identified as the manufacturer "confirmed that they did not produce the certificate, and that they were not the originator of the part,” EASA said.