A government official, who spoke on condition of anonymity, told AFP the investigation showed the accident was due to mistakes on the part of the crew piloting the jet when it went down in stormy weather on January 25, 2010.
An earlier preliminary report on the crash said the accident was due to pilot inexperience and a series of errors by the pilots who failed to take into account signals emitted by the plane's instruments.
The pilot erroneously believed the jet was on automatic pilot and as a result he and his co-pilot failed to heed the alarm signals as the plane veered dangerously off course before crashing, the preliminary report showed.
The Ethiopian Airlines Boeing 737-800 went down minutes after taking off from Beirut international airport, killing 83 passengers and seven crew.
Lebanese officials have previously said that data recovered from the plane's black box showed all instruments were working well until it plunged into the Mediterranean in a fierce storm.
They have also ruled out sabotage.