Drift Matsuri NZ event organiser Chris Howard told the Herald he was contacted by police a day after the drift event about an alleged sexual assault.
Howard said park security had also contacted him about the alleged incident.
The event, New Zealand Spring Drift Matsuri 2018, showcased drift motorsport, and featured live DJs, an on-site R18 after-party, food trucks and a licensed bar.
Howard said he understood the interaction was between a man and a woman.