MANILA (Reuters) - Philippine President Rodrigo Duterte has threatened corrupt government officials with the prospect of being thrown out of a helicopter mid-air, warning he has done it himself before and would do it again.

File photo - Then-local mayor of Davao city Rodrigo Duterte (R), aboard a helicopter, arrives at the provincial capitol in Tagum city, Davao del Norte, southern Philippines for the Regional Peace and Order Council meeting, April 20, 2015. REUTERS/Lean Daval Jr.

The fiery-tempered former prosecutor said he once hurled a Chinese man suspected of rape and murder out of a helicopter.

“If you are corrupt, I will fetch you using a helicopter to Manila and I will throw you out. I have done this before, why would I not do it again?” Duterte told typhoon victims in a speech on Tuesday, a clip of which is posted on a video feed of the president’s office.

Duterte’s latest threat came a few weeks after he admitted killing people during his 22 years as a mayor of Davao City, sometimes riding a motorcycle looking for “encounters to kill.” Some senators have warned Duterte he risks impeachment over his comments.

The United States, a long-time Philippines ally which has expressed concern about Duterte’s war on drugs and his anti-American rhetoric, said it was aware of his statements about the helicopter.

“As we have stated previously, we are deeply concerned by reports of extrajudicial killings by or at the behest of government authorities in the Philippines,” State Department spokeswoman Anna Richey-Allen said in an emailed response to a Reuters inquiry.

Duterte has repeatedly said those killings were part of legitimate police operations, including a hostage incident, and those killed were criminals, not suspects.

It was not immediately clear when or where the helicopter incident Duterte spoke of took place.

In an interview on Thursday with Philippine news channel ABS-CBN, Duterte was non-committal when asked about the incident.

“Helicopter to throw a person?” he asked. “And if that is true, I will not admit it.”

His spokesman, Ernesto Abella, suggested earlier the story was an “urban legend.”

Duterte also said six people arrested last week during a seizure of more than half a tonne of methamphetamine, known locally as “shabu”, 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.”

The United Nations’ top human rights envoy has called for an investigation into Duterte’s claims of killing people, to which Duterte last week responded by calling him “stupid,” an “idiot” and a “son of a bitch” who should go back to school.