A member of the Renault team known only as Witness X finished the Formula One career of Flavio Briatore and could yet lead the Italian to be banished from football.

Evidence from the “Crashgate” inquiry released late last night detailing the most explosive case of cheating in sporting history damns Briatore, the former managing director of the Formula One team and owner of Queens Park Rangers Football Club.

Briatore was banned for life from motor-racing activities, including managing drivers, after the hearing in Paris on Monday held by the FIA, Formula One’s governing body, for his role in the conspiracy that forced Nelson Piquet Jr to crash his Renault in the 2008 Singapore Grand Prix so that Fernando Alonso, his team-mate, could win.

But Briatore is also under pressure to walk away from QPR as fans, lawyers and politicians told The Times that they believe he cannot continue, morally or legally, as a key figure in any sport.

Briatore was protesting his innocence yesterday and said that he would take legal action to clear his name. But the extent of his connivance was laid bare by a whistleblower within the Renault team — referred to in the FIA evidence as Witness X and whose identity is known only to a handful of insiders, including Max Mosley, the FIA president.

Witness X came forward on the eve of the FIA World Motor Sport Council hearing to reveal the elaborate details of the plot as Renault executives struggled to piece together events in their internal inquiry.

According to Witness X, Briatore knew all about the plan and the architect was Pat Symonds, Renault’s once highly respected director of engineering.

The FIA statement said: “Witness X was told of the idea suggested by Nelson Piquet Jr by Mr Symonds, whilst in the presence of Mr Briatore. Witness X objected to the idea. He did not know the plan was to be carried into effect until the crash happened.

“As a result of the evidence, including Mr Piquet’s admission, Mr Symonds’s responses and Witness X’s evidence, Renault F1 concluded that they and Mr Briatore must have known about the conspiracy.”

The trio kept the plan secret from the rest of the team, which explains why the FIA was keen to go easy on Renault, handing out a two-year suspended ban to the manufacturer team, while cracking down on Briatore and Symonds, who was banned from motor racing for five years. Piquet was given immunity for revealing the plot.

The FIA dismissed Briatore’s suggestion that he had no knowledge of the affair and refused to accept his version of events, ruling he was “personally and directly involved in the planning of the conspiracy”. Even worse, Briatore was Piquet’s manager at the time.

Symonds is revealed as a victim of Briatore’s demanding regime. He was a longstanding employee of Renault — known as Benetton and Toleman before the French company took control. While Briatore refused to attend the FIA hearing on Monday, Symonds rejected the chance of immunity but wrote a letter expressing his “eternal regret and shame”.

“I was the one who, when the idea was first suggested to me by Nelson Piquet Jr, should have dismissed it immediately,” he said. “I can only say I did it out of a misguided devotion to my team and not for any personal gain whatsoever. I consider the role I have played in bringing the team to where it is today to be my life’s work.

“In a single action, I have destroyed the high reputation I have built up during a 33-year career in motor sport.”