LISBON, July 13 (Reuters) - Portugal's prosecutors have named the country's largest utility EDP a formal suspect in an ongoing corruption investigation that caused the suspension of its CEO from his duties last week, the company said on Monday.

Without revealing further details, a spokesperson told Reuters EDP had been notified by the prosecutor's office after Artur Trindade, former energy secretary of state, was also named a suspect for allegedly benefiting the firm in exchange for unspecified favours. (Reporting by Sergio Goncalves, Writing by Catarina Demony, Editing by Andrei Khalip)