The UFC has decided to hold off on any plans concerning a comeback for BJ Penn after recent criminal allegations against the former lightweight champion.

Penn, 37, announced in recent months that he intends to come out of a retirement that began in July 2014. He has been training at Jackson Wink MMA in Albuquerque, New Mexico, and had expressed a desire to return at UFC 197 on April 23 in Las Vegas.

According to the Delaware, Ohio, county sheriff's office, a 29-year-old woman reported an assault by Penn on Aug. 31, 2015, in the state of Hawaii.

The report indicates that the matter has been referred to police in Hilo, Hawaii, where Penn is from.

"UFC is aware of the recent allegations made against BJ Penn," the group said in a release Thursday. "The organization requires all athletes who compete in the UFC to act in an ethical and responsible manner, as detailed in the UFC Fighter Conduct Policy.

"Every athlete is deserving of proper review, and this situation, as with any serious allegation, will be investigated by an independent party and thoroughly reviewed by the UFC. In light of the serious allegations, UFC has postponed plans to book Penn for an upcoming bout until more details are determined."

The UFC inducted Penn (16-10) into its Hall of Fame last year.