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One of the two black box flight recorders from the EgyptAir plane that crashed in the Mediterranean last month has been repaired after arriving in France, as investigators attempt to unravel the mystery behind the tragic event.

The black box recorder "has been successfully repaired by the French accident investigation agency laboratory", the commission said in a statement.

"Tests have been carried out and we can be sure the flight parameters were properly recorded," the investigators said.

"Work to repair the second black box will commence tomorrow."

On Monday, the crucial flight recorders arrived in France for repairs.

The arrival of the flight recorders came as French judges were tasked with probing the May 19 crash of the plane which had 15 French citizens among the 66 aboard, prosecutors said.

Prosecutors had previously opened a preliminary investigation – a normal procedure when French citizens are involved – and have handed their findings to judges for a full-fledged probe into "manslaughter".

The black box flight recorders were found two weeks ago, but were too damaged to extract information on what caused the crash.

Investigators have said it is too early to determine what caused the plane to crash, although a terror attack has not been ruled out.

France's aviation safety agency has said the aircraft transmitted automated messages indicating smoke in the cabin and a fault in the flight control unit minutes before it disappeared.

Egyptian investigators confirmed the aircraft had made a 90-degree left turn followed by a 360-degree turn to the right before hitting the sea.

The Airbus A320 was en route from Paris to Cairo when it crashed in the Mediterranean, with 40 Egyptians on board as well as two Iraqis, two Canadians and one each from Algeria, Belgium, Britain, Chad, Portugal, Saudi Arabia and Sudan.