Josh Barnett's Bellator debut has been pushed back yet again.

The former UFC heavyweight champion is out of his Bellator 241 fight against Ronny Markes because of what Mohegan Tribe Department of Athletic Regulation director Mike Mazzulli described Wednesday as a failed medical test. Mazzulli declined to elaborate.

UFC veteran Matt Mitrione will replace Barnett against Markes, Bellator officials said. The event is scheduled for March 13 at the Mohegan Sun in Uncasville, Connecticut.

"Mr. Barnett has failed a medical requirement by the Mohegan Tribe Department of Athletic Regulation and will not be fighting on the March 13 Bellator event," Mazzulli said. "He will not be allowed to fight until he resolves the failed test."

Bellator said in a statement that Barnett "was not licensed by the commission." Barnett's team did not respond to a request for comment Wednesday.

This marks the second time that Barnett's Bellator debut has been delayed. He was supposed to make his debut with the promotion against Markes in December but fell ill the day of the fight and was not cleared to compete by the Hawaii commission.

Barnett, 42, has had several failed drug tests in his career. In 2002, he was stripped of the UFC heavyweight title because of a positive test for steroids. Barnett failed another test in 2009, when he was on the verge of a big main event under the Affliction banner against Fedor Emelianenko. USADA, the UFC's anti-doping partner, flagged Barnett in 2016 for a banned substance but later cleared him after more than a year of investigation.

After asking for and being granted his UFC release due to distrust of USADA, Barnett signed with Bellator last year.

Barnett (35-8) is one of MMA's most decorated heavyweights. In 23 years as a pro, the Washington state native has defeated the likes of Randy Couture, Dan Severn, Antonio Rodrigo Nogueira and Mark Hunt.