A preliminary report into the Air India crash that killed more than 200 people last month showed three seconds after taking off, the plane's engines fuel cutoff switches almost simultaneously flipped from run to cutoff, starving the engines of fuel.

The Boeing 787 Dreamliner immediately began to lose thrust and sink down, according to the report released on Saturday by Indian aviation accident investigators.

One pilot can be heard on the cockpit voice recorder asking the other why he cut off the fuel. "The other pilot responded that he did not do so," the report said.

It did not identify which remarks were made by the flight's captain and which by the first officer, nor which pilot transmitted "mayday, mayday, mayday" just before the crash.

The preliminary report also does not say how the switch could have flipped on the June 12 London-bound flight from the Indian city of Ahmedabad.

'You can't bump them and they move': expert

U.S. aviation safety expert John Cox told Reuters a pilot would not be able to accidentally move the fuel switches that feed the engines. "You can't bump them and they move," he said.

Flipping to cutoff almost immediately cuts the engines. It is most often used to turn engines off once a plane has arrived at its airport gate and in certain emergency situations, such as an engine fire. The report does not indicate there was any emergency requiring an engine cutoff.

"At this stage of investigation, there are no recommended actions to Boeing 787-8 and/or GE GEnx-1B engine operators and manufacturers" India's Aircraft Accident Investigation Bureau said. The agency, an office under India's civil aviation ministry, is leading the probe into the world's deadliest aviation accident in a decade.

Air India, Boeing and GE Aviation did not respond immediately to requests for comment.