An investigator into missing flight MH370 has cast doubt on claims by air safety experts that the captain was conscious at the moment the plane crashed into the ocean, saying such a scenario was “unlikely”.

But Peter Foley, who is coordinating the international search, did not rule out that pilot Zaharie Ahmad Shah deliberately crashed the airliner in a carefully planned murder-suicide mission.

He also admitted for the first time that the Australian Transport Safety Bureau (ATSB) believes a pilot was in control of the airliner for at least the first 90 minutes after it veered off course.

Mr Foley was being quizzed by an Australian senate committee on theories espoused in Canadian air crash investigator Larry Vance’s new book, MH370: Mystery Solved.

“It’s absolutely evident… an aircraft doesn’t turn itself,” he said. “Certainly there were flight controls early in the flight.”

The book argues that two wing flaps found on islands off Africa in 2015 and 2016 point to Shah performing a controlled ditching, outside the 46,000 square miles that were scoured by sonar in a £112m search that ended last year.

MH370: Mystery for missing Malaysia Airlines flight remains unsolved

It says Shah's aim was to keep the plane largely intact so it would disappear as completely as possible in the remote southern ocean.

But the ATSB still believes the airliner probably ran out of fuel and crashed after flying far off course en route from Kuala Lumpur to Beijing four years ago.

It believes all 239 passengers and crew on board were likely long dead inside a depressurised cabin and cockpit.

Mr Foley, who said he has read the book, pointed to evidence the plane was not under anyone's control when it hit the water.

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He said analysis of the satellite transmissions of the flight's final moments showed the jet was in a fast and accelerating descent at the end. Debris from within the plane's interior found washed up on the west coast of the Indian Ocean suggested significant energy on impact.

“If it was being controlled at the end, it wasn't very successfully being controlled,” Mr Foley said. “The flaps weren't deployed.”

The book argues that the two recovered flaps show evidence that they had been deployed, as the pilot slowed the plane for a gentle landing on water.

Mr Foley said an analysis at the bureau's headquarters in Canberra of the second flap found on the island of Pemba, off the coast of Tanzania, in June 2016 determined it was “probably not deployed”.

But French authorities prevented an Australian analyst from “doing anything meaningful in terms of analysis” of the first flap found. That flap, known as a flaperon, was found on the French island of Reunion in July 2015. French authorities are holding the flaperon as evidence for a potential criminal prosecution.

Mr Foley said his bureau could not conclude that the flaperon had lost its trailing edge because it was deployed when the plane hit the water.

While the bureau has not said who had initially flown the plane off course, Mr Foley said “it's absolutely evident” that someone had, ruling out some mechanical or electrical malfunction.

Texas-based technology company Ocean Infinity renewed the search this year on the basis that Malaysia would pay it up $70 million if it could find the wreckage or the plane's black boxes.

Mr Foley said he still hopes the search will succeed within weeks.

“If they're not, of course, that would be a great sadness for all of us,” he added.