A heavyweight title fight between Alexander Povetkin and Bermane Stiverne was called off after it was revealed that the Russian boxer failed a drugs test just hours before they were due to step into the ring.
Povetkin and Canadian Stiverne were set to do battle in Ekaterinburg on Saturday, but the interim title bout was cancelled after the former tested positive for banned substance ostarine.
World Boxing Council president Mauricio Sulaiman tweeted: "The @WBCBoxing is officially withdrawing recognition of Povetkin vs Stiverne due to the positive result of Povetkin for ostarine."
Povetkin was scheduled to face Deontay Wilder in May, but that fight was also postponed after the Russian tested positive for meldonium.
Haiti-born Stiverne is quoted as saying by ESPN: "There's no reason to fight if the WBC won't sanction the bout.
"I'm very disappointed in the actions of Povetkin. I've been training for months to be victorious. To wake up the day of the fight, have breakfast, take a nap and wake up to find out he tested positive is the worst possible situation."
WBC cruiserweight world champion Tony Bellew tweeted: "Right had enough of this now! BAN these drug cheats for life! How many more does Povetkin need to fail? Fail for PED's you have to banned!
"I'm sick of saying it! This isn't a race it's a FIGHT! Lives are at risk! A stance needs to be made he's failed 3! BAN HIM FOR LIFE!"