An ongoing investigation into the 2016 EgyptAir flight crash has revealed that the incident had been caused by a cockpit fire, not explosives, which had previously been suggested by Egyptian authorities.

France's Civil Aviation Accident Bureau (BEA) - ran their own inquiry into the case after Egyptian authorities had "not followed up calls for further investigations and instead blamed an alleged bombing," according to The Independent. 

The Airbus A320 crashed into the southeastern Mediterranean while flying from Paris to Cairo on May 19, 2016, leaving 66 people dead.

According to Reuters,12 French nationals were among those killed in the crash. In December 2016, Egyptian officials announced that "traces of explosives were found" on victims' remains.

However, a French-led investigation tends to disagree with this conclusion.

"The BEA considers that the most likely hypothesis is that a fire broke out in the cockpit while the airplane was flying at its cruise altitude and that the fire spread rapidly resulting in the loss of control of the airplane," said BEA in a statement. 

Two days after the crash in May 2016, the flight data recorder "confirmed the presence of smoke on board," according to the BBC. 

The cockpit recorder also "captured the conversation in the cockpit about a fire".

According to a source who spoke on condition of anonymity to The Independent, discrepancies surrounding the investigation may be due to the "political differences between France and Egypt".

However, Egyptian investigators had not published their final report, says BEA. This has made it impossible for them to understand how different conclusions were reached.

"This is big"