The boxer is well known for high profile bouts with Floyd Mayweather and Mancunian hero Ricky Hatton.
The staggering claim by the fighter-turned-politician is an attempt to support the controversial Filipino president Rodrigo Duterte.
More than 3,000 drug dealers and drug-takers have been killed since June as part of a government crackdown in the country.
?I tried drugs? many kinds of drugs, all kinds of drugs,? Pacquiao said in an inteview.
Pacquaio, 37, and Duterte have a strong relationship and the boxer is said to be the president?s close ally.
Speaking from his senate office, Pacquiao said: ?God put [Duterte in power] for purpose to discipline the people.?
The devout Roman Catholic is hugely popular in the boxing world for his calm and relaxed manner outside the ring.
Pacquiao who experts see as one of the best pound-for-pound fighters of his generation said his drug abuse happened years ?before I became a champion?.
