By Stephanie Holmes ROME, Jan 26 (Reuters) - Italian police on Saturday seized aircraft parts belonging to Panaviation, a company at the center of a large-scale investigation into suspected fraudulent sale of second-hand aircraft parts to major airlines. Police said people found stripping an Airbus A300 plane belonging to Panaviation at Rome's Fiumicino airport on Saturday morning were not qualified to do the job. Investigators said they were looking into any possible link between Panaviation parts and two air crashes -- an Airbus which crashed into the New York suburb of Queens last November, killing 265, and a domestic airline accident in Italy in 1999. "We are checking. We now have the documentation to see if there is a link," police chief Anselmo Mocci told Reuters. The head of brokerage firm Panaviation Enzo Fregonese, under house arrest in Rome, told Reuters he was unable to comment. His lawyer, Grazia Volo, also declined to comment. In Washington, U.S. aviation authorities confirmed they were working with the FBI, which is conducting a probe into possible criminal activity. "It's an FBI investigation and all I can say is that we're cooperating with those authorities," U.S. Federal Aviation Authority spokeswoman Diane Spitalieri told Reuters. "If it's an unapproved aircraft part that is being sold, that is criminal. That's a criminal act." Investigators suspect that some used parts might have been sold as new or else passed on with misleading documentation. Italy's Air Safety Authority said the results of the inquiry would have far-reaching implications for the airline industry. "It will shake the whole aviation world," spokesman Adalberto Pellegrino told Reuters. OPERATION WITHOUT PRECEDENT Three Rome-based brokerage companies are under investigation for allegedly providing reconditioned parts, some with false certificates, to national and international airlines, police said. In what financial police describe as an operation without precedent in terms of size, 150 police officers raided factories and companies suspected of illegal parts sales. The financial police said in a statement late on Friday: "We have ascertained that Panaviation, New Tech Italia and New Tech Aerospace obtained, reconditioned and sold a large quantity of aeronautical material." Police said the parts were sold on to major Italian airlines including Alitalia, Minerva and Meridiana as well as European and U.S. airlines. The Fiumicino raid was the second seizure of parts following the confiscation on Friday of aircraft parts from a ship in the port of Naples, police chief Mocci said. "We took about 1,000 pieces in two containers from Fiumicino," Mocci told Reuters. "The parts in Naples were destined for the United States, but we do not yet know where these were heading." Six people are under house arrest following the investigations. Police, who said they were collaborating with both the FAA and the FBI, said the airline parts seized were worth a total of 2.7 million euros ($2.3 million). Investigators looking into the Queens crash were focusing on engine failure and rudder malfunction as possible causes. After a Minerva airlines jet plunged off the runway into the sea at Genoa in 1999, the pilot was found guilty of malpractice, but he said there were problems with the braking system.