France is the only country still looking into the disappearance of Malaysia Airlines flight MH370. French investigators who have studied the Boeing's flight data have encountered some new suspicious details about the flight.

Ghyslain Wattrelos, a French engineer who lost his wife and two teenage kids in the MH370 tragedy, claims that the doomed plane was carrying some mysterious cargo.

He has told the newspaper Le Parisien, citing French investigators that “there are several contradictory passenger lists, for example on the placement of passengers”.

It also emerged that a “mysterious load of 89kg” had been added to the flight list after take-off, along with an overloaded container, he said.

“The expert draws no conclusion. It may be incompetence or manipulation", he was quoted as saying. “Everything is possible. This will be part of the questions for the Malaysians".

Malaysian authorities have failed to establish why the plane with 239 souls on board made a detour en route from Kuala Lumpur to Beijing and vanished from radar screens.

An extensive underwater search in the southern Indian Ocean, where the plane is believed to have crashed, has found no trace of the Boeing. Several pieces of debris, which likely belonged to the aircraft, have been found off South Africa, Madagascar, and Mauritius.

There have been various and often contrasting theories as to the cause of the tragedy. One of them suggests that the Boeing could have been hijacked – either by a pilot, a passenger, or a stowaway.

The discovery of the 89-kilogram load could substantiate the latter hypothesis, which self-styled MH370 sleuths have floated in the past.

Last month, aviation security expert Tim Termini told Channel 5’s Flight programme: “I think it’s highly likely that a hijack took place – and again, there’s four options for the hijack".

“One is the hijack of the aircraft through a crew member".

“The second is a hijack coming from a passenger".

“A third option, which is a fairly unusual one, would be a stowaway".

“And then of course the fourth option is an electrical takeover of the aircraft from a ground-based station".

Philip Baum, editor of the academic journal Aviation Security International and aviation security professor, has claimed officials don’t seem to want to contemplate the possibility of a stowaway.

“I think a stowaway is a strong possibility, especially as no officials seem to want to even contemplate the possibility", he told The Independent in 2018.

He said that one or more individuals could have gotten on board the plane while it was grounded at the airport and hidden in the underfloor electronics and engineering bay behind the flight deck.