Enzo Maccarinelli has been given a six-month anti-doping suspension after testing positive for methylhexaneamine (MHA).
The former WBO cruiserweight champion was tested following his win over Shane McPhilbin on March 23, where UK Anti-Doping found traces of the banned substance.
The ban has been backdated to April 19 and will expire on October 18.
UK Anti-Doping chief executive Andy Parkinson said: "This is a timely reminder that, no matter what your sport, under the principle of strict liability athletes must exercise extreme caution over what they put into their body.
"With this in mind, Olympic athletes should be aware that they are now in-competition from 16 July until 12 August and could be tested at anytime, anywhere. MHA is available in a range of supplement products, is banned in-competition, and can often be listed under a number of different names.
"UK Anti-Doping continues to work closely with the British Boxing Board of Control to maintain the integrity of the sport."
Maccarinelli boasts a record of 35 wins from 40 fights, 27 of which have come via knockout.
