(CNN) The Philippine President vowed Friday to keep up his controversial campaign against drugs as long as he remains in office.

Rodrigo Duterte was met with a roar of approval and chants of "Duterte, Duterte" when he took to the stage in Singapore to address members of the Filipino community.

He said he would not stop "until the last drug pusher and the last drug lord are..." at which point he drew his finger across his neck in a dramatic execution-style gesture.

"Look; it can never be a crime to say, 'I will kill you if you destroy my country,'" he added, asking the appreciative crowd to look at the crime rate. "Almost gone," he said. "Ask your relatives back home."

Public attention to the controversial campaign intensified Monday when Duterte admitted to personally killing drug suspects during his time as mayor of Davao City.

"In the crawlers of CNN and BBC, since yesterday, it's said 'Duterte admits killing, shooting criminals,'" the president announced to a booing crowd. "They're not wrong."

Later, back in the Philippines, Duterte said he had killed three people, then said he was among a group firing weapons and he had no way of knowing if his bullets were the ones who struck their targets.

"When I tell you now that I killed, do not term them as suspects," he said. "Because all of them died while they were fighting government people.

"At least I killed to protect people. I am not a dictator killing my political opponents to stay in power."

'Under the United States for 50 years'

During his speech, Duterte also lashed out at US criticism of his policies.

The Millennium Challenge Corporation, a US government aid agency, said this week it "deferred a vote on the reselection of the Philippines" for development, "subject to a further review of concerns around rule of law and civil liberties."

The release did not elaborate on the value of the aid package.

"We were under the US for 50 years. You live off the fat of the land, you got the best of our worlds and you threatened to cut our aid, so I said to Obama: 'Go to hell,'" said Duterte.

"We are members of the United Nations, correct? If there's something that you are against in my policies or behavior, go to the United Nations and complain. Then the UN and its organs or agencies will investigate. Then and only then, when there's a report submitted to the assembly, bring it to the floor," he stressed.

"Don't reprimand me like I'm your boy. I am the President of the Republic of the Philippines," he added.

Mounting controversy

The strongly worded speech comes amid mounting criticism of Duterte's violent efforts to rid the Philippines of its endemic drug problem.

The Philippine National Police released figures Monday showing that 5,927 people have died in the war on drugs since July 1. More than 2,000 were killed in police operations and the rest were victims of extrajudicial or vigilante-style killings.

This week, news emerged of a 6-year-old shot dead as he slept next to his father, an occasional drug user.

Senator Leila de Lima, one of Duterte's top critics, called Thursday for the President to be impeached.

"These are mass murders," de Lima told CNN . "High crime is a ground for impeachment under (the) constitution."

Duterte on Trump

Duterte said he had hoped Donald Trump would be elected US president because he likes Trump's personality and the way he speaks. He said Trump told him that Duterte was handling his country's drug problems the right way.

But a good rapport with the next president will not be enough to heal the rift he has with the United States, Duterte said.

Support at home

Duterte's public approval rating remains near 80 percent, according to Social Weather Stations, an independent polling agency. Many in the Philippines are fed up with decades of crime and government corruption and say Duterte has made the public safe, particularly in Davao.

"You can walk in the street. No danger. Because we have no drug addicts," fish vendor Imelda Rulete said.

Student Ryan James Villarmia added, "In the name of human rights, it's sad. But for the safety of the people, it's good."