Williams, a former World Cup-winning All Blacks rugby star, won the controversial heavyweight bout on points in Brisbane last Friday, which was marred by unsubstantiated reports that Botha failed a drugs test.
Botha, 44, alleges Williams’ manager Khoder Nasser offered him the money in a Brisbane park three days before the World Boxing Association fight, claiming he received a phone call asking to pick him up alone.
“I wasn’t told where I was going. As we stopped at a park, my cellphone was confiscated and was given to a guy in the car,” Botha told New Zealand’s Radio LiveSport from Durban.
“Then I was being walked (by Nasser), and during this walk, I was offered Aus$150,000 to throw the fight. I just said ‘no, I can’t do it’,” he added.
There is no suggestion that Williams was aware of the alleged offer. Nasser slammed Botha as a bad loser after a fight that ended in 10 rounds, despite earlier promotions saying it was a 12-round contest.