French investigators are probing the possibility that two electronic devices may have brought a passenger jet down.

EgyptAir Flight 804 crashed into the Mediterranean sea on May 19, 2016, killing all 66 people on board. 

According to French newspaper Le Parisien, the batteries inside the co-pilot's iPhone 6s and iPad mini 4 may have exploded mid-flight, causing a fire that led to the disaster.

Surveillance video recorded at the gate at France's Charles de Gaulle airport before the flight took off for Cairo in Egypt showed the phone and tablet sitting on the right-hand corner of the plane’s dashboard along with four bottles of perfume.

The spot where the items were last seen was also the first location where the  automatic warning messages signaled problems before the plane crashed.

All electronic devices are powered by lithium-ion batteries. When they catch fire it is a process called thermal runaway, a rapid, uncontrolled chemical reaction within the battery that causes the internal temperature to rise.

When one cell in a battery overheats it can produce enough heat - up to 900°C (1652°F) - to cause adjacent cells to overheat. This can cause a lithium battery fire to flare repeatedly.

Federal Aviation Administration data in the USA reveals that in just nine years battery-powered devices were involved in 113 incidents with "smoke, fire, extreme heat or explosion" on passenger and cargo planes.

* A pioneering invention called an AvSax can minimise the fire danger in seconds with its unique use of water.

Simply pour at least two litres of water into an AvSax and then drop the burning device into the bag. The water activates a polymer gel inside the bag’s lining causing it to expand around the device. Should the device keep on burning then the AvSax is tough enough to absorb the force.