Tough-talking Philippine President Rodrigo Duterte came under criticism Wednesday after boasting that he “personally” killed suspected criminals when he served as mayor of Davao City.

While it was not the first time Duterte appeared to admit to murder, this was the first time he’d done so as president. And it outraged critics of his country’s bloody war of drugs, which has left at least 4,500 Filipinos dead in the last five months.

Philippine President Rodrigo Duterte reviews honor guards during a departure ceremony at the Manila International Airport in Pasay City, south of Manila, Philippines, 13 December 2016. Duterte will visit Cambodia to boost bilateral ties, then he will pay a vitist to Singapore, which he stated are preparations for the Philippine chairmanship of the Association of Southeast Asian Nations (ASEAN) in 2017. MARK R. CRISTINO / EPA

“By boasting about the blood on his own hands, President Duterte will further embolden police and vigilantes to blatantly violate laws and carry out more extrajudicial executions without fear of being held to account,” Amnesty International said Wednesday. “President Duterte should be fulfilling his obligations by ordering investigations into these killings and bringing those responsible to justice, not claiming a part in them.”

Earlier, Duterte’s justice minister Vitaliano Aguirre II appeared to walk back his boss’ controversial claim, saying the president “exaggerated” and that if he did kill anybody it “must have been forced.”

But it was this kind of incendiary language about killing criminals that endeared Duterte to crime-weary Filipinos.

During the 20 years he was mayor of Davao City, Duterte was nicknamed “the death squad mayor” after teams of hit men began rubbing out the city’s drug dealers and addicts. He denied any role in the vigilante action but he praised the killings.

Duterte made the killing admission in a speech Monday to a group of businessmen.

“In Davao, I used to do it personally,” Duterte said. “Just to show the guys that, if I can do it, why can’t you?”

“And I’d go around in Davao with a motorcycle, with a big bike around, and I would just patrol the streets, looking for trouble also. I was really looking for a confrontation so I could kill.”

Duterte also told the group he would not be bullied into stopping the harsh crackdown on criminals in light of criticism from President Obama or human rights groups.

“Sorry, I am not about to do that,” he said.

Duterte then appeared to double down on his claims while on a state visit Tuesday to Cambodia, according the Manila Times.

This picture taken on October 29, 2016 shows police officers investigating a crime scene where two alleged drug dealers were gunned down by unidentified men in Manila. Business has never been busier for undertaker Alejandro Ormeneta but, after five months on the frontlines of the Philippines' brutal drug war, he just wants the killings to stop. NOEL CELIS / AFP - Getty Images

I (would) sometimes go along with them. If you say I shot someone, maybe I did. I was closing my eyes because I am scared of firing a gun,” said Duterte.

Back in 2015, Duterte admitted killing at least three men in Davao City suspected of kidnapping and rape. He was elected president the next year.