Paolo Basarri has left his position as the compliance officer of Formula 1's governing body the FIA.
Multiple sources, both at and close to the FIA, said the Italian had been fired as a consequence of FIA president Mohammed Ben Sulayem losing confidence in him.
The FIA has declined to comment, while Basarri told BBC Sport: "I cannot comment on this."
Basarri is the official who compiled a report into allegations that Ben Sulayem interfered in the operations of two races during the 2023 season.
A whistleblower told the FIA Ben Sulayem had intervened to overturn a penalty given to Aston Martin’s Fernando Alonso at the 2023 Saudi Arabian Grand Prix, and that he allegedly told officials not to certify the Las Vegas circuit for its race last year.
Ben Sulayem was cleared of the allegations following an investigation by the FIA ethics committee.
BBC Sport has been told Basarri left the organisation last week.
According to FIA rules, the compliance officer's role is managed by the FIA Senate, which is required to give its permission if he is fired, but his position was not discussed at a meeting of the Senate this week, sources say.
Basarri is the second senior figure to leave the FIA in a week, following the departure of F1 race director Niels Wittich.
The FIA said Wittich had "stepped down". The German told BBC Sport on Thursday: "I can confirm that I got fired and it was not my decision to leave F1."
The departures of Basarri and Wittich follow a trend in the past year of the FIA losing senior figures.
Sporting director Steve Nielsen quit in December 2023 after less than a year in his role. His departure followed that of Deborah Mayer, head of the FIA commission for women.
In January, leading engineer Tim Goss left his role as single-seater technical director, and is now at Red Bull's RB team.
Natalie Robyn left her role as chief executive officer in May after just 18 months.
And in October, director of communications Luke Skipper and secretary general of mobility Jacob Bangsgaard were added to the list.
The departures come amid a series of controversies surrounding Ben Sulayem's leadership.
The latest incident was a letter published last week by the Grand Prix Drivers' Association in which they asked to be treated like adults in the wake of Max Verstappen and Ferrari's Charles Leclerc being punished for swearing.