LOS ANGELES - A dispute over doping test rules for the planned showdown between Manny "Pac-Man" Pacquiao and Floyd Mayweather Jnr has jeopardised the long-awaited welterweight bout scheduled for March 13.

It is uncertain whether the testing issue is an over-hyped negotiating ploy aimed at Pacquiao or truly a deal-breaker that could scuttle a fight that could be the biggest boxing moneymaker of all time.

Mayweather has insisted on stricter World Anti-Doping Agency (Wada) test procedures rather than the usual methods, a change that would require blood tests for banned substances as well as urine analysis.

Mayweather's father, veteran trainer Floyd Mayweather Snr, has accused Pacquiao of taking performance-enhancing substances, and Mayweather all but accused the Filipino hero of being a dope cheat.

"I have already agreed to the testing and it is a shame that he is not willing to do the same," Mayweather said.

Richard Schaefer, top executive of Golden Boy Promotions, said that Todd du Boef, president of Top Rank, told him Pacquiao would not agree to have blood drawn within 30 days of the fight.

Schaefer said Du Boef told him Pac-Man was superstitious about having blood taken so near a fight. He wants it done before a planned news conference in early January to launch the fight, which is expected to happen on March 13.

"Team Mayweather is surprised that an elite athlete like Manny Pacquiao would refuse drug-testing procedures that Floyd has already agreed to," said Schaefer.

Leonard Ellerbe, chief executive of Mayweather Promotions, said the fight would be off if Pacquiao did not agree to the testing. - Sapa-AFP