Air France has confirmed that the crew of the aircraft lost en route between Rio de Janerio and Paris Charles received a electrical fault message.
The aircraft transmitted the message to the crew at 02:14UTC, which would have been about four hours after departure.
While Air France has not publicly confirmed the aircraft type, aircraft addressing system data identifies it as an Airbus A330-200.
A spokesman for the airline says that the "crew received a message says there was a fault in an electrical circuit". He declines to expand.
Unconfirmed reports suggest the aircraft had been experiencing turbulent weather conditions shortly before the transmission.
Search efforts are underway to locate the aircraft, which was operating flight AF447 with 228 passengers and crew on board.