NASCAR star Tony Stewart has been questioned but not charged by police after an altercation at a Sydney track.

New South Wales state police spokesperson Joanne Elliott said Sunday that the 39-year-old Indiana driver, who is in Australia competing in sprint-car races, was released after being interviewed at the Rosehill police station in western Sydney.

"Police from Rosehill central command were alerted to an altercation involving two men at a race car track about 7:30 last night," Elliott said. "A 39-year-old man was arrested at the scene after a 46-year-old man was allegedly hit in the face by a racing helmet.

"The 39-year-old man was released without charge, pending further investigation."

Several auto racing websites reported that the altercation at Sydney Speedway resulted from Stewart being upset about track conditions and that the other man involved was speedway co-owner Brett Morris.

Stewart was reportedly scheduled to leave Australia on Sunday. The police spokesperson said there was no reason to expect that he wouldn't be allowed to leave as scheduled.

Phone and e-mail messages to Sydney Speedway seeking comment from Morris weren't immediately returned.