MANILA — The head of the police Criminal Investigation and Detection Group (CIDG) read former President Rodrigo Duterte his Miranda rights during his arrest on an International Criminal Court warrant linked to his war on drugs.

“Sir, you have the right to remain silent. You have the right to counsel of your choice,” CIDG chief Maj. General Nicolas Torre III told Duterte in a video posted by the latter’s daughter Veronica on Instagram.

“Anything you say may be used for and against you in a court of law,” Torre added.

Asked if he understood his rights, Duterte said, “Of course, coming from you, it’s very clear.”Prosecutor General Richard Anthony Fadullon said authorities “observed due process” by reading Duterte his rights and “ensuring that the dignity of the former President is protected.”

He added that questions on the validity of the warrant “should be raised before the court that issued it and not before the arresting officers implementing the same.”

The 79-year-old faces a charge of “the crime against humanity of murder”, according to the ICC, for a crackdown that rights groups estimate killed tens of thousands of mostly poor men, often without proof they were linked to drugs.

“Early in the morning, Interpol Manila received the official copy of the warrant of the arrest from the ICC,” Malacanang said.

“As of now, he is under the custody of authorities.”

The statement added that “the former president and his group are in good health and are being checked by government doctors”.

But Duterte demanded to know the basis of his arrest in another video posted to his youngest daughter Veronica’s Instagram account following his detention.

“So what is the law and what is the crime that I committed? Show to me now the legal basis of my being here,” he said in the video.

“I was brought here not of my own volition but somebody else’s … you have to answer now for the deprivation of liberty.”

While no location was given for the video, a photo released by his political party said he was being held at the Villamor Air Base next to Manila airport.

Duterte’s former chief legal counsel, Salvador Panelo, called the arrest “unlawful”.

“The (Philippine National Police) didn’t allow one of his lawyers to meet him at the airport and to question the legal basis for PRRD’s arrest,” he said, adding a hard copy of the ICC warrant had not been provided.

Reactions from those who opposed to the drug war, however, were jubilant.

One group that worked to support mothers of those killed in the crackdown called the arrest a “very welcome development”.

“The mothers whose husbands and children were killed because of the drug war are very happy because they have been waiting for this for a very long time,” Rubilyn Litao, coordinator for Rise Up for Life and for Rights, told AFP.

“Now that Duterte has been arrested, (President) Ferdinand Marcos Jr. should make sure that he is actually delivered to the ICC for detention and trial,” said Philippine rights alliance Karapatan, calling the arrest “long overdue”.

Human Rights Watch also called on the government to “swiftly surrender (Duterte) to the ICC”, saying the arrest was a “critical step for accountability in the Philippines”.