LAS VEGAS – Jon Jones is accused of a drug-testing violation and his title unification bout with Daniel Cormier in the main event of UFC 200 on Saturday at T-Mobile Arena is off.

UFC president Dana White made the announcement in a hastily called news conference Wednesday night. White said he was at dinner at Stripsteak at Mandalay Bay when he got the news shortly before 7 p.m. Pacific time.

White said the heavyweight bout between ex-champion Brock Lesnar and Mark Hunt would be the main event, though it will remain a three-rounder. White said he would keep Cormier on the card if possible, but said he didn’t want it to be against someone who had no shot.

Jones could face a two-year sanction if found guilty of the violation.

Jeff Novitzky, the UFC’s vice president of athlete health and performance, read a prepared statement and took no questions.

“The UFC organization was notified tonight that the U.S. Anti-Doping Agency has informed Jon Jones of a potential anti-doping policy violation stemming from an out-of-competition sample collection on June 16,” Novitzky said. “USADA, the independent administrator of the UFC anti-doping policy, will handle results management and appropriate adjudication of this case.

“It is important to note that under the UFC anti-doping policy, there is a full, fair legal review process that is afforded to all athletes before any sanctions are imposed. However, because Jones was scheduled to compete against Daniel Cormier this coming Saturday, July 9, in Las Vegas, there is insufficient time for a full review before the scheduled bout. Therefore, the bout has been removed from the fight card.”

White said Jones has a chance to prove himself innocent, but said he didn’t know if Jones had requested the B sample to be tested.

Under the policy, which is the same as is done in the Olympics, Jones has the right to have his B sample tested to make sure the results are consistent. When an athlete is tested, the sample is split into A and B bottles and the B sample is held in the event the A sample becomes positive.

Though the UFC did not announce what Jones tested positive for, it would have to be a performance-enhancing drug that is on the World Anti-Doping Agency’s prohibited list. Drugs of abuse, such as cocaine, are banned only in the 24 hours prior to competition.

It is why Jones was permitted to fight Cormier at UFC 182 on Jan. 3, 2015. He tested positive for cocaine, but because the positive came more than 24 hours before the competition, it wasn’t a violation and the UFC was unable to pull him from that card.

Jones made no statement and his manager, Malki Kawa, did not return a message seeking comment.

Jones has a checkered UFC history. Though he’s considered the greatest MMA fighter in history, he has run into all sorts of trouble outside of the Octagon. He pleaded guilty to driving under the influence in 2012, and had a hit-and-run auto accident in 2015. Later that year, he got into a widely publicized argument with an Albuquerque, N.M., police officer, when he was pulled over in a traffic stop.

His fight with Cormier was the main event of what was to be the biggest show of the year. Cormier, who answered questions at the news conference, appeared devastated, but he took the high ground.

“At times, I was very hard on him,” Cormier said of Jones. “But at the end of it, whether he was doing bad, who am I to be the moral police? I’ve made a lot of mistakes. I’ve done some things in my life that are terrible. I’ve been through a divorce because of things I had done outside of my marriage. I’ve done a lot of negative things in my life.

“I try to improve on them as I move forward. … I’m not the moral police. I really don’t care all that much.”