Lewis Hamilton said Formula One is facing a "pivotal moment" as it battles a series of off-track controversies early in the new season.
The buildup to last weekend's season-opening Bahrain Grand Prix was overshadowed by the fallout caused by Red Bull's investigation into alleged inappropriate behavior by team boss Christian Horner.
On Tuesday, the FIA, motorsport's governing body, said its compliance department was "assessing" reports that its president, Mohammed Ben Sulayem, told officials not to certify the track used for last year's Las Vegas Grand Prix.