Robert Reid, deputy president for sport at the FIA, has resigned over what he describes as "a fundamental breakdown in governance standards within motorsport's global governing body".
The Scot was a key member of FIA president Mohammed Ben Sulayem's leadership team when the Emirati was elected in 2021 but the pair have since fallen out amid a series of controversies surrounding the FIA president.
Reid said in a statement that he was experiencing "growing alarm over critical decisions being made without due process or proper consultation".
"When I took on this role, it was to serve the FIA's members, not to serve power," Reid said.
"Over time, I have witnessed a steady erosion of the principles we promised to uphold.
"Decisions are being made behind closed doors, bypassing the very structures and people the FIA exists to present."
Reid's resignation follows changes to the FIA statutes at the last FIA General Assembly that opponents have described as "a worrisome concentration of power" and a reduction in accountability.
Reid's move also comes after MotorsportUK chairman David Richards wrote an open letter to the organisation's members accusing the FIA of a "shift of moral compass".