Manila (AFP) – Former Philippines president Rodrigo Duterte was arrested Tuesday in Manila by police acting on an International Criminal Court (ICC) warrant tied to his deadly war on drugs.

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,” the presidential palace said in a statement.

“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”.

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.

But a group that worked to support mothers of those killed in Duterte’s drugs 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.

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