MANILA -- Former Philippines leader Rodrigo Duterte was sent to The Hague on Tuesday hours after he was arrested in Manila at the request of the International Criminal Court as part of its probe into a "war on drugs" that defined his presidency.

Duterte, a maverick ex-mayor and former prosecutor who led the Philippines from 2016 to 2022, was arrested early on Tuesday, marking the biggest step yet in the ICC's probe into alleged crimes against humanity during an anti-drugs crackdown that killed thousands and drew condemnation around the world.

Duterte, 79, could become the first Asian former head of state to go on trial at the ICC.

"The plane is en route to the Hague, in the Netherlands, allowing the former president to face charges of crimes against humanity in relation to his bloody war on drugs," Philippine President Ferdinand Marcos Jr told a press conference.

"We did not help the International Criminal Court in any way. The arrest was made in compliance with Interpol."

The war on drugs was the signature campaign platform that swept to power the mercurial crime-buster nicknamed "the punisher", who soon delivered on promises he made during vitriolic speeches that thousands of drug pushers would be killed.

His detention follows years of him rebuking and taunting the ICC in profanity-laden speeches since he unilaterally withdrew the Philippines from the court's founding treaty in 2019 as it started looking into allegations of systematic murders of drug dealers on his watch.

The ICC, a court of last resort, says it has jurisdiction to investigate alleged crimes that took place while a country was a member.

Duterte has long insisted he instructed police to kill only in self-defense and has always defended the crackdown, repeatedly telling his supporters he was ready to "rot in jail" if it meant ridding the Philippines of illicit drugs.

Human rights groups and families of victims said Duterte's arrest was a decisive step toward accountability for a brutal and chilling campaign that targeted the poorest of Filipinos.

"This is only the start of our fight. Our justice has not yet been achieved because there's still a lot of things that will happen, but we will not stop fighting," said Llore Pasco, 70, the mother of two drugs war victims.

Slumland killings

According to police, 6,200 suspects were killed during anti-drug operations under Duterte's presidency that they say ended in shootouts. But activists say the real toll was far greater, with many thousands more slumland drug users gunned down in mysterious circumstances, some of whom were on community "watch lists" having signed up for treatment.

The prosecutor of the ICC has said as many as 30,000 people may have been killed by police or unidentified individuals.

Police have rejected allegations from rights groups of systematic murders, staged crime scenes and fabricated incident reports.

Duterte, in livestreamed remarks while in custody, told police he should be tried in a court in the Philippines.

"Why will you bring me to an international body when we are no longer a member?" he asked. "Ponder on it seriously, because this will have implications."

The arrest caused outrage among the family, loyalists and supporters of the still popular Duterte, who called it an affront to Philippine sovereignty.

"They took dad from us, put him on a plane and wouldn't say where to. People, wake up," his youngest daughter Veronica Duterte posted on Instagram. She said her father had been "kidnapped".

Duterte's closest aide, Christopher "Bong" Go, a senator, said: "Long gone are the days when foreigners dictated how we run our internal affairs."

Fall from grace

The arrest marks a stunning change of fortunes for the influential Duterte family, which formed a formidable alliance with Marcos to help him win a 2022 election by a huge margin, with Duterte's daughter, Sara Duterte as his vice president.

But the two had a bitter fallout, culminating in Sara Duterte's impeachment last month by a lower house led by loyalists of Marcos, and signals from the president that he would comply if an arrest warrant was issued for his predecessor, having previously vowed not to help the ICC.

Police investigations in the Philippines have moved at a snail's pace, by the administration's own admission, and neither Duterte nor any of his top police commanders have been charged with crimes locally.

The ICC on Tuesday said Duterte was charged with the crime of murder as a crime against humanity and bore criminal responsibility for the alleged murder of at least 43 people between 2011 and 2019.

The warrant said judges were satisfied there were reasonable grounds to conclude Duterte was head of a death squad that operated when he was mayor of southern Davao City and later oversaw Philippine law enforcement when he became president.

Leila de Lima, a former justice minister who was jailed under Duterte, months after she led a Senate investigation into the killings, said the families of victims were courageous in bringing him to justice.

"Your voices mattered, your courage mattered," she said.