1137 GMT December 18, 2018
Saunders had tested positive for oxilofrine in a Voluntary Anti-Doping Association (VADA) test, Reuters reported.
The stimulant is banned by VADA while it is prohibited only during competition by World Anti-Doping Agency and UK Anti-Doping.
British media reports said the 29-year-old Saunders could be stripped of the belt he won in 2015 if he fails to get a license for his scheduled title defense on October 20.
Saunders has denied any wrongdoing in the matter and said that the adverse analytical finding was the result of using a common decongestant nasal spray.