Pacquiao has recently railed at corruption in government as well as the president’s friendly relationship with China.

“When you are a champion in boxing, it does not mean to say that you are a champion in politics,” Duterte told a media briefing. “He is blubbering his mouth.”

Pacquiao, 42, had long been among Duterte’s strongest supporters, but is seen as a possible contender when Duterte’s single six-year term ends.

Duterte asked why the boxer-turned-lawmaker was only talking about corruption now – and said he should focus on investigating graft rather than leaving the country to prepare for a fight next month.

“I would say that you are s***,” Duterte said. “Start investigating. Comply first with your duty as senator. Don’t be absent.”

Pacquiao’s office said he would respond at a news conference on Saturday. He and Duterte belong to the same political party, which is urging the president to run for vice-president next year.