MH370 US tech giant Apple revealed yesterday that it had assisted US authorities in their search for missing Malaysia Airlines flight MH370.

"When the Malaysia Airlines plane went down, within one hour of that plane being declared missing, we had Apple operators cooperating with telephone providers all over the world, with the airlines, with the US Federal Bureau of Investigation (FBI) to try to find a ping, to try to find some way we could locate where that plane was," Apple general counsel Bruce Sewell said.

He said this while being grilled for five hours at a US House of Representatives committee hearing over Apple's stance on encryption yesterday.

The Verge reported Sewell as saying this when asked how Apple would handle hypothetical emergencies, such as if clues to a forthcoming nuclear explosion were locked in an iPhone.

The Apple representative said the company would have attempted to find "all of the data that surrounds that phone", adding that Apple had cooperated in other emergencies, including in the 2014 search for MH370.

Apple is on the hot seat for resisting an FBI request to create a backdoor that would allow authorities to break into an iPhone used by one of the attackers in the San Bernardino mass shooting late last year.

Flight MH370 had disappeared on March 8, 2014 while en route from Malaysia to Beijing.

The plane is believed to have crashed in the South Indian Ocean, although the mass of its wreckage has yet to be found.

This theory was strengthened after a flaperon belonging to the ill-fated plane was discovered on Reunion Island last year.