The WBO will re-score Jeff Horn's controversial win over Manny Pacquiao, but the Australian is keeping the welterweight title.

Pacquiao and the Philippines Games and Amusements Board (GAB) called for the WBO to review the "unfair decision and officiating" that led to his shock defeat on Sunday.

Pacquiao lost the welterweight title to Horn by unanimous points decision in Brisbane, the seventh loss of the veteran fighter's career, despite appearing to have the better of the fight and coming close to stopping the Australian in round nine.

The judges ruled 117-111, 115-113 and 115-113, much to the dismay of the boxing world as most agreed Pacquiao was the more efficient boxer.

The WBO said in Thursday's public letter to GAB the only hope of revoking the fight judges' decision rests on proving fraud in match officiating.

The result of the fight will not be changed regardless of the ruling.

"I would be very grateful if the GAB can provide any evidence indicating fraud or violation of law," WBO president Francisco Valcarcel said.

"The purpose of this review is to be able to give the fans certainty of who was the winner of the bout, even though we do not have the power to reverse the decision of the judges based on discretion and, in this case, we do have a rematch clause on the fight contract."

The WBO plans to have five anonymous judges review the bout, creating their own scores to each round. 

"Then, we will tabulate the results to ascertain clearly which rounds each fighter won using an average scale based on 60, 80 and 100 percent," Valcarcel said.

"This means that three of the five officials have to agree to determine which fighter won the round."