A preliminary report into the deadly crash of an Air India jetliner in June is expected to be released by Friday, three sources with knowledge of the matter said, with one adding the probe had narrowed its focus to the movement of the plane's fuel control switches.

While the report from investigators could be made public on Friday, the three sources cautioned Reuters that plans could change and there was no clarity on how much information would be available in the document,

The much-awaited preliminary report on the devastating Air India crash, involving a Boeing Co. BA +1.68% Get Free Report airplane, in June, which claimed 260 lives, is expected to be released by the end of this week.