Manny Pacquiao plans to sue Floyd Mayweather, the American's father and Golden Boy Promotions in the next few days following a row over doping procedures, the Filipino world champion said.
"Enough is enough. These people, Mayweather Sr., Jr., and Golden Boy Promotions, think it is a joke and a right to accuse someone wrongly of using steroids or other performance-enhancing drugs," Pacquiao said.
"I have tried to just brush it off as a mere pre-fight ploy but I think they have gone overboard."
The WBO welterweight title bout between Mayweather Jr and champion Pacquiao scheduled for next March was called off last week after the American demanded Olympic-style dope testing and Pacquiao said his reputation had been damaged enough.
"I have instructed my promoter, Bob Arum, head of Top Rank Inc., to help me out in the filing of the case as soon as possible because I have had people coming over to me now asking if I really take performance-enhancing drugs and I have cheated my way into becoming the No. 1 boxer in the world," he said.
"I have no idea what steroids look like and my fear in God has kept me safe and victorious through all these years," added the 31-year-old Filipino who has never tested positive.
Mayweather's camp had called for random blood and urine sampling prior to and after the highly-anticipated March 13 fight as mandated by the US Anti Doping Agency.
Pacquiao agreed to have blood taken for testing before the initial media conference and immediately after the fight but would not agree to have blood drawn within 30 days of the bout.
Arum said using blood tests was unprecedented for professional fights in Las Vegas but more extensive testing agreeable to Pacquiao could have been arranged.
"We don't object to more extensive drug testing, even though it's certainly not required in Nevada," he told Reuters.
"What we're saying is that the drug testing he (Mayweather) is proposing is intrusive and would disturb Pacquiao's training if it's done within 30 days of his fight."
Arum had suggested the testing demands by Mayweather were a way of ducking a fight in which Pacquiao was due to defend the World Boxing Organisation title he won in November by stopping holder Miguel Cotto in the 12th round in Las Vegas.