French air investigators said on Saturday that Airbus had detected faulty speed readings on its A330 jets ahead of last week's crash and had recommended its clients replace a sensor.

Theories about the crash have focused on the possibility that airspeed sensors malfunctioned, leading the pilots to set the wrong speed as the plane passed through storms.

The Air France plane set 24 automated messages indicating a series of system failures before it vanished, said Paul-Louis Arslanian, the head of France's Air accident agency.

In the middle of this steam of data was one message showing inconsistent speed readings from the A330's sensors.

Airbus confirmed it issued a bulletin asking the Plane's 50 airline operators to consider changing the speed sensors, but it said it was an optional measure to improve performance and not related to safety.

Arslanian also said in a news conference that it was too soon to say if problems with the pressure-based speed sensors were in any way responsible for the disaster.

Some of the sensors (on the A330) were earmarked to be changed…but that does not mean that without these replacement parts, the Air France plane would have been defective, he said.

Problems had been detected (on A330s) and we are studying them, he said, adding that the plane was safe to fly.

Airbus also issued a reminder late Thursday that pilots should follow standard procedures -- to maintain flight speed and angle -- if they thought their speed indicators were faulty.

Meteorological experts said the jet crossed a storm zone but that the weather did not seem to pose a particular threat.

Investigators are not optimistic that they will be able to locate the plane's flight recorders.