PARIS, July 2 (Reuters) - French heavyweight Tony Yoka has been ruled out of a WBA title bout with Russia's Murat Gassiev due to a back injury, L'Equipe and other media reported on Thursday.
Gassiev, previously the secondary 'regular' world champion, is in line to inherit the belt relinquished by Ukrainian 'super champion' Oleksandr Usyk last month.
The bout with Yoka, arranged before Usyk's announcement, was scheduled for July 11 in Moscow but L'Equipe confirmed a report by boxing journalist Dan Rafel that the 2016 Olympic champion had withdrawn.
Yoka, ranked 14th by the WBA, had been due to fight British heavyweight Lawrence Okolie last April but his opponent failed a dope test and that clash did not happen.
The heavyweight division has been fragmented by Usyk's announcement, with German boxer Agit Kabayel recently declared the WBC champion.
Britain's Daniel Dubois holds the WBO belt while the IBF title remains vacant.
(Reporting by Alan Baldwin; editing by Clare Fallon)
