French investigators said in a statement the flight data recorder, or black box, had been hauled up to the deck of a search boat.

The Airbus A330-200 plane plunged into the Atlantic off the northeast coast of Brazil en route to Paris from Rio de Janeiro in June 2009, killing all 228 passengers and crew on board after the flight hit stormy weather.

Officials from France's BEA air accident inquiry office said it was too early to say whether the black box, which records data from the plane's instruments but no voices, would yield any information.

"One thing that's clear is that even if the box does not look damaged on the photograph, we cannot say whether it works until we have opened it up," a BEA spokeswoman told Reuters.

"That requires very precise equipment and the analysis can only start in a Paris laboratory."

She said search robots had already dived back to the Atlantic sea floor to try to find the second black box, which contains voice and sound recordings from the cockpit.

Pictures on BEA's website of the box before it was pulled to the surface showed an orange cylindrical object half-buried in sand.

The structure housing the recorder appeared to be intact and remarkably free of corrosion.

The name of its manufacturer -- U.S. electronics company Honeywell -- was clearly readable on the side as a robot arm was seen plucking the cylinder from the seabed.

The discovery came after long searches of a 10,000 square kilometer area of sea floor.