Reports in the British media suggest accusations against Renault's F1 team go beyond it fixing the result of the 2008 Singapore Grand Prix.
The Independent newspaper is quoting a source within the sport's governing body, the FIA, as saying "other issues above and beyond Singapore are also to be looked at".
It also says the investigations into the alleged wrong-doing began at Spa-Francorchamps last weekend, with engineering boss Pat Symonds and Fernando Alonso among "senior Renault figures" interviewed multiple times.
However, former Renault test driver Franck Montagny has said he "did not believe" the claims could be true.
"Even when you are asked to let someone pass it is annoying," he said, "but to be made to deliberately have an accident is really something else."