European regulators have pinpointed a potentially flawed cleaning process during maintenance as investigators probe an engine fire that caused a Cathay Pacific Airbus jet carrying 348 people to turn back to base.

A cleaning process leading to fuel hose degradation during refurbishment may have caused a recent Airbus A350 engine fire that triggered dozens of Cathay Pacific flight cancellations this month, the EU aviation regulator said Thursday.

The engine defect in the Airbus A350 plane that led to the cancellation of dozens of Cathay Pacific flights in early September could have escalated into "extensive damage", according to