He said those killings were part of legitimate police operations, including a hostage incident. Some senators have warned Mr Duterte he risks impeachment over his comments.
Mr Duterte also said six people arrested last week during a seizure of more than half a ton of methamphetamine, known locally as “shabu”, in the capital were fortunate he was out of town.
“They were lucky I was not in Manila that time. If I had known there were that much shabu inside a house, I would definitely kill you,” he said.
“Let’s not make any drama, I will personally gun you down if nobody else will do it.”
It was not immediately clear when or where the helicopter incident Mr Duterte spoke of took place. His spokesman, Ernesto Abella, suggested it may not have actually happened.
“Let’s just say, ‘urban legend’,” Mr Abella told reporters, without elaborating.
The United Nations’ top human rights envoy has called for an investigation into Mr Duterte’s claims of killing people, to which the Philippines’ president last week responded by calling him “stupid”, an “idiot” and a “son of a bitch” who should go back to school.