The US Federal Aviation Administration is investigating whether false or falsified documents were used to verify the authenticity of titanium used in some recently built Boeing jets, the agency said.

The New York Times, which first reported on the issue on Friday, said the FAA is also investigating the authenticity of documents on titanium used in some Airbus jets.

Aircraft manufacturers are facing strong demand for new planes due to the rise in travel after the pandemic. However, supply-chain problems and component shortages are limiting their ability to meet this demand.

Titanium is a critical component in the aerospace supply chain and is used to make landing gear, blades and turbine discs for aircraft.

The FAA said Boeing “has made a voluntary disclosure regarding the purchase of material through a distributor that may have submitted false records or provided incorrect information.”

The agency added: “Boeing has issued a bulletin informing suppliers how to be alert to the potential for falsified records.”

Boeing said the issue was industry-wide and that some titanium shipments were received from a limited number of suppliers, affecting parts of the aircraft.

The aircraft manufacturer said it was removing all such parts from the aircraft before delivery and added that this would not have any impact on safety.

Airbus said it was aware of the reports, but added that “numerous tests have been carried out on parts coming from the same source of supply. They show that the A220’s airworthiness remains intact.”

Canada has imposed sanctions on Russian titanium, although with some exceptions. It is unclear whether the false documents were linked to the sanctions.

Spirit AeroSystems, which supplies fuselages for Boeing and wings for Airbus, said titanium had entered the supply chain with “false” documents, and all related parts have been removed from its production.

“More than 1,000 tests have been completed to verify the mechanical and metallurgical properties of the impacted material to ensure its flight worthiness,” Spirit said.

Last year, jet engine maker CFM International revealed that thousands of its engine parts may have been sold by a British distributor on the basis of forged documents.

The discovery prompted airlines to replace parts on some planes.

Boeing shares fell 1.8%, while Spirit shares lost nearly 1%.