Two-time Sprint Cup champion Tony Stewart was fined $10,000 and his team was placed on probation Monday following an altercation last week at the U.S. Auto Club's National Midget race in Indianapolis.
Stewart was fined for unsportsmanlike conduct and conduct detrimental to racing.
USAC said in a statement that Stewart was involved in an on-track incident Thursday at O'Reilly Raceway Park related to one of his Midgets driven by points leader Tracy Hines. Hines had scraped the wall and pitted for a tire change, but his car was not deemed ready to re-enter the race in time to rejoin the field for the restart.
Stewart then came down to pit lane to get an explanation for the call. He reportedly knocked the headset from the official's head and then shoved him.
"USAC immediately assessed the incident and it was determined that unacceptable behavior detrimental to the sport had occurred, and that the professionalism and the integrity of the series and its promoters had been severely compromised," Jason Smith, USAC's vice president of racing operations, said in the statement. "While we respect the passion of our teams in the spirit of competition, we regret this incident occurred and are dedicated to averting a recurrence in the future."
Stewart, who apologized Monday, also agreed to pay for the costs of new radios and uniforms for USAC officials.
"My own misinterpretation of USAC policies in place at the time led to confusion and elevated emotions," Stewart said. "I'm very passionate about my race team and will stand up for them when I think something isn't right. Obviously, I handled this particular situation the wrong way, and if I had to do it over again, it never would've happened."