AN AMERICAN "plane hunter" has been warned he will be KILLED if he continues to probe the mysterious disappearance of flight MH370, it's been reported.

Blaine Gibson first hit the headlines in February 2016 when he claimed he had found debris from the Malaysian Airlines jet washed up on a sandbank in Mozambique.

4 Gibson holding pieces of plane debris found on Nosy Boraha island, Madagascar Credit: EPA

The two foot metal fragment had the words 'No Step' written on its side and was said to be from the doomed passenger jet.

Gibson has since found more than 16 pieces of suspected wreckage which turned up on the Indian Ocean islands of La Reunion, Rodrigues, Madagascar and Mauritius and the coastlines of South Africa.

However, a respected aviation expert has now revealed since making his startling finds, the self-proclaimed adventurer has been receiving chilling death threats.

William Langewiesche, a pilot turned writer, told the Atlantic after the sleuth found the first piece of wreckage "he began receiving death threats."

"One message said that either he would stop looking for debris or he would leave Madagascar in a coffin.

"Another warned he would die of polonium poisoning...He has been traumatised," he added.

4 The American 'plane hunter' has reportedly received death threats since making his finds Credit: EPA

4 Officers carrying a flaperon from an aircraft apparently washed ashore in Saint-Andre de la Reunion, eastern La Reunion island Credit: EPA

Langewiesche said he hooked up with Gibson in Kuala Lumpur where he is in "hiding", reports The Sunday Times.

“He largely avoids disclosing his location or travel plans, and for similar reasons avoids using email and rarely speaks over the telephone," the author revealed.

"He frequently swaps out his Sim cards. He believes he is sometimes followed and photographed."

And conspiracy theorists believe self-funded Gibson has every reason to be running scared.

They point to the fact a diplomat investigating the disappearance was gunned down just as he was about to deliver "new evidence" to Malaysian investigators.

Honorary Consul of Malaysia Zahid Raza was shot dead in Madagascar's capital Antananarivo in an apparent assassination in September 2017.

4 A Boeing 777 flaperon cut down to match the one from flight MH370 found on Reunion island off the coast of Africa

Wreckage washed up thousands of miles away from the official MH370 search area Credit: Aidan Ellis

At the time Gibson revealed he was left severely rattled by news of the killing.

He said he had planned to keep details of his latest finds under wraps until they had been safely transported off the island but changed his mind after Mr Raza was killed.

“For the protection of those involved we decided not to make this report public until the debris was safely delivered to Malaysia,” Mr Gibson reported in his blog.

“However tragic events have intervened. Under the agreement between the two countries, debris is supposed to be collected by Hon. Zahid Raza, the Honorary Malaysian Consul in Madagascar, and delivered by private courier to Malaysia.

“On August 24, the Hon. Zahid Raza was assassinated in Antananarivo.”

Malaysian Airlines flight 370 vanished on March 8, 2014, 40 minutes into a flight from Kuala Lumpur to Beijing, with 239 people on board.

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Satellite data indicates it travelled south for several hours before crashing into the remote southern Indian Ocean off Western Australia.

However, a three-year search by the Australian Transport Safety Bureau (ATSB) failed to find any trace of the plane.

A second mission by underwater exploration company Ocean Infinity last year also failed to locate the wreckage.

Malaysia Airlines flight MH370 went missing on March 8, 2014, with 239 passengers and crew on board Credit: Alamy