A cockpit recording of dialogue between the pilots in the deadly Air India crash apparently suggests the captain cut the fuel to the plane’s engines.

According to a source, First Officer Clive Kunder was at the controls of the Boeing Dreamliner 787-8 and can be heard asking Captain Sumeet Sabharwal why he moved the fuel switches into a position that starved the engines of fuel.

Kunder also requests that Sabharwal restore the fuel flow, the American source told Reuters on condition of anonymity because the matter remains under investigation.

They said the US assessment wasn’t outlined in any formal document and the cause of the June 12 crash in Ahmedabad, India, that killed 260 people remained under investigation.

The early assessment is that the weight of evidence from the conversation points to the captain, despite no cockpit video recording definitively showing which of the two pilots flipped the switches.

The Wall Street Journal first reported similar information on Wednesday about the world’s deadliest aviation accident in a decade.

India’s Aircraft Accident Investigation Bureau, which is leading the investigation into the crash, said on Thursday that “certain sections of the international media are repeatedly attempting to draw conclusions through selective and unverified reporting”.

It added the investigation was ongoing and it remained too early to draw definitive conclusions.

A preliminary report released by the AAIB on Saturday said one pilot was 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,” it said.

Investigators did not identify which remarks were made by Sabharwal and which by Kunder, who had total flying experience of 15,638 hours and 3403 hours, respectively.

The AAIB’s preliminary report said the fuel switches had switched from “run” to “cutoff” a second apart just after takeoff. It did not say how they were moved.

Almost immediately after the plane lifted off the ground, closed-circuit TV footage showed a backup energy source called a ram air turbine had deployed, indicating a loss of power from the engines.

The London-bound plane began to lose thrust, and after reaching a height of 200 metres, the jet started to sink.

The fuel switches for both engines were turned back to “run”, and the plane automatically tried restarting the engines, the report said.

But it was too low and too slow to be able to recover, aviation safety expert John Nance told Reuters.

The plane clipped some trees and a chimney before crashing in a fireball into a building on a nearby medical college campus, the report said, killing 19 people on the ground and 241 of the 242 on board the 787.

In an internal memo on Monday, Air India chief Campbell Wilson said the preliminary report found no mechanical or maintenance faults and that all required maintenance had been done.

The AAIB’s preliminary report had no safety recommendations for Boeing or engine manufacturer GE.

After the report was released, the US Federal Aviation Administration and Boeing privately issued notifications that the fuel switch locks on Boeing planes are safe, a document seen by Reuters showed, and four sources with knowledge of the matter said.

The US National Transportation Safety Board has been assisting with the Air India investigation. Its chair Jennifer Homendy had been fully briefed on all aspects, a board spokesperson said.

“The safety of international air travel depends on learning as much as we can from these rare events so that industry and regulators can improve aviation safety,” Homendy said.

“If there are no immediate safety issues discovered, we need to know that as well.”

The circumstantial evidence increasingly indicated that a crew member flipped the engine fuel switches, Nance said, given there was “no other rational explanation” consistent with the information released to date.

-AAP