Montreal boxer Lucian Bute maintains he never took any illegal substances.
Earlier this year Bute tested positive for a banned substance called ostarine.
Now a second sample has also tested positive.
Bute claims a product he used to help him sleep was contaminated with ostarine, and says this has been confirmed by tests requested by his lawyer.
"I am happy because never I took something illegal. Today I prove I am clean," said Bute.
Bute says he is considering taking legal action against the lab which conducted the tests.
The boxer still has to go before the ethics commission.
