The UFC has released welterweight Matt Riddle after he tested positive for marijuana for a second time.

Riddle, 27, is a medical marijuana user, but had agreed to stop taking the drug three weeks prior to a fight.

However, he got his schedule wrong leading up to his bout against Che Mills at UFC London and tested positive after the fight.

Speaking recently, the American said: "I do smoke but I'm not smoking to get stoned. I'm smoking so I can finally relax, sit back and just not worry about things.

"People, maybe they did it in college one way, but for a guy like me, for a professional athlete that goes through what we go through, it's medicine for me. Maybe for some little stoner sitting on the couch playing Xbox, for him, it's a drug. For me, it's medicine."

Riddle had won his four previous bouts.