The World Boxing Organisation has refused to sanction Nathan Cleverly's world title shot with Robin Krasniqi at London's Royal Albert Hall on 28 April.
The WBO gave Cleverly permission to fight Tommy Karpency in February as long as their champion's next defence was against their mandatory challenger.
And Cleverly was told to fight Russian Dmitry Sukhotsky within 120 days of beating American Karpency on points.
The WBO say Cleverly's Krasniqi bout "cannot and would not be sanctioned."
The fight could go ahead as a non-title fight but if promoter Frank Warren wants Cleverly's fourth defence to be a WBO world title fight, the opponent will have to be changed to 30-year-old Sukhotsky.
But Warren wanted the undefeated Welshman to fight Serbian Krasniqi in what he was hoping to be the first world title show at the Albert Hall in over a decade.
Warren announced the Krasniqi clash at a London press conference on Tuesday lunchtime but the WBO issued a statement on their website almost immediately.
The statement said: "Francisco Valcarcel commented that because Nathan Cleverly's sanction against Karpency clearly stated that the bout was being sanctioned with the provision that the winner fight his mandatory bout 120 days from the day of the bout, subject to the WBO Regulations of World Championship Contests."
Cleverly was due to be the first Welshman to appear in a world title fight at the Albert Hall since Howard Winstone beat Mitsunori Seki to win the WBC featherweight crown in January 1968.
The 25-year-old's fight was to be on the same night as Bernard Hopkins's WBC world light-heavyweight title rematch with Chad Dawson in Atlantic City.
And Warren then wanted the winners of the two fights to meet in the summer.
