The bitter, high-speed world championship feud between Valentino Rossi and Marc Marquez has "poisoned" motorcycling, the sport's chief said.
Rossi, the nine-time world champion, was blasted for kicking defending champion Marquez off his bike at Sepang on Sunday.
As a result, the veteran Yamaha rider has been relegated to the back of the grid for the season finale in Valencia on November 8.
Should his chief rival and teammate Jorge Lorenzo win on home ground in Spain, Rossi must come second to clinch the title.
But Rossi insists he is the victim of a Spanish plot and has accused Honda star Marquez of pursuing a "dirty game" with the express intention of helping compatriot Lorenzo to the title.
Such is the atmosphere of suspicion that Vito Ippolito, the president of the International Motorcycling Federation (FIM),penned an open letter on Thursday in a plea for peace amongst the paddock's warring factions.
"The recent events arising in connection with the competition for the 2015 world title have had a damaging effect on the staging of our competitions and poisoned the atmosphere around the sport," wrote Ippolito.
"We are moving away from the tradition of pride in sportsmanship that is part of the heritage of motorcycling.
"Everyone has the right to express his or her own ideas. But words and actions always have consequences. Every individual has to take responsibility for those consequences."
Rossi goes into the season-decider with a narrow seven-point lead over Lorenzo while Marquez is out of contention after an injury-plagued season.
Teammates Lorenzo and Rossi have a history of tense relations, which erupted again following Sunday's Sepang clash.
The Spaniard said Rossi should have been punished even more severely but that his superstar status shielded him.
"The championship is not over yet but this sanction cut me off by the legs," said Rossi.
He called the punishment unfair, saying Marquez is "making me lose the championship".