The data recorder of an EgyptAir plane that crashed in the Mediterranean Sea last month indicates there was smoke on board the aircraft, investigators said Wednesday.

EgyptAir Flight 804 from Paris to Cairo went down on May 19, killing all 66 people on board. Despite initial fears of terrorism, no militant group has claimed responsibility and the precise cause of the crash remains unknown.

The Egyptian investigating committee said in a statement that the recovered flight data recorder, one of the plane's black boxes, showed that there was smoke in the lavatory and onboard equipment.

The statement also said that wreckage from the Airbus A320's front section showed "signs of damage because of high temperature", as well as soot.

The second black box, a cockpit recorder, was damaged in the crash and is being repaired in Paris. The wreckage was recovered from the Mediterranean Sea floor earlier this month. The bulk of the wreckage is believed to be at a depth of about 9,800 feet.

The committee said deep ocean search teams are still working to find and recover human remains.

French authorities opened a manslaughter inquiry on Monday, but said there is no evidence so far to link the crash to terrorism.

EgyptAir Flight 804 disappeared from radar between the Greek island of Crete and the Egyptian coast. Data showed the aircraft had been cruising normally in clear skies before it turned 90 degrees left, then a full 360 degrees to the right as it plummeted from 38,000 feet to 15,000 feet. It disappeared when it was at an altitude of about 10,000 feet.

The Associated Press contributed to this report.