The black boxes recovered from the wreckage of an Egyptair plane that crashed in the Mediterranean a month ago are badly damaged, meaning that extracting data will take considerable time, sources in the investigation committee said on Sunday.
The memory units in the cockpit voice recorder and the flight data recorder, which were recovered from the sea last week, both suffered "severe damage," the sources said.
An official statement from the committee, also released on Sunday, said it had completed the process of drying out the units, which took eight hours, and they were now undergoing electrical testing.
The statement made no reference to the extent of damage to the memory units. The committee previously said that the black boxes, which also contain other parts, were found in several pieces.
Egyptair flight MS804 was en route from Paris to Cairo on May 19 when it crashed into the Mediterranean, some 290 kilometres north of the Egyptian coast, killing all 66 people on board.
The Airbus A320 veered to the left and then spun around rightwards in the last minutes before it crashed, according to Greek and Egyptian officials. No distress call was received.
The sources said the memory units were being evaluated to see whether experts in the Egyptian Ministry of Civil Aviation will be able to repair them or whether they would have to be sent abroad.
It would be impossible to extract the data from the two units - one of which records voices and sounds in the cockpit, while the other gathers technical data from the aircraft's equipment - before carrying out the repairs, they added.
Shakir Qallad, the former director of the Egyptian air accident investigation committee, said that the process of extracting the data could take "a long time, maybe weeks" in addition to the time needed to repair the units.
Last month, Egyptian Civil Aviation Minister Sherif Fathy said that a terrorist act appeared a more likely cause than mechanical failure.
The crash came almost six months after a Russian passenger jet broke up midair shortly after take-off from the resort of Sharm el-Sheikh in Egypt's Sinai peninsula, killing all 224 people on board.
Russian authorities said that the incident was caused by a bomb. The Islamic State extremist group, which operates in Sinai, claimed responsibility and published a photo of a soft drink can that it said had been filled with explosives and smuggled onto the flight.