Former Philippines president Rodrigo Duterte said he was "responsible" as the International Criminal Court took him into custody Wednesday to face charges of crimes against humanity over his war on drugs.

The ICC, based in The Hague, believes there are "reasonable grounds" to charge Duterte with murder as a crime against humanity, as an "indirect co-perpetrator" during the anti-drug campaign that rights groups estimate killed tens of thousands.

"I am the one who led our law enforcement and military. I said that I will protect you and I will be responsible for all of this," Duterte told his country, in a video shared on his and a close advisor's Facebook pages as he was about to land.

"I have been telling the police, the military, that it was my job and I am responsible," said the 79-year-old, the first Asian former head of state to face charges at the ICC.

The court rules on the world's worst crimes, including war crimes, crimes against humanity, and genocide. A spokesman confirmed Duterte was in court custody after he arrived in Rotterdam by private jet.

A vehicle thought to be carrying Duterte drove into the ICC detention center in The Hague past a crowd of dozens of supporters, some shouting: "Bring him back" and waving national flags.

"There has been no due process," said caregiver Duds Quibin, 50. "This is kidnapping. They just put him on a plane and brought him here," he told AFP.

The center, located close to the North Sea coast, offers each prisoner an individual cell equipped with a computer to work on their case, along with an outdoor exercise area.

Duterte will be held here until an initial court appearance, likely in the coming days.

Speaking to AFP outside the ICC, Gilbert Andres, a lawyer representing victims of the drug war, said: "My clients are very thankful to God because their prayers have been answered."

"The arrest of Rodrigo Duterte is a great signal for international criminal justice. It means that no one is above the law," Andres added.

'Oppression and persecution'

Before her father's departure, Vice President Sara Duterte said he was being "forcibly taken to The Hague," labelling the transfer "oppression and persecution."

A one-time alliance between President Ferdinand Marcos and the Duterte family has exploded spectacularly since the 2022 presidential election, when Sara Duterte was Marcos's running mate.

She is currently facing a Senate trial on a number of charges, including corruption and an alleged assassination plot against Marcos.

Duterte himself had earlier taken to social media, claiming the Supreme Court would step in and prevent his transfer.

At a church in the capital Manila, people whose family members were killed in the "drug war" welcomed the arrest.

"Duterte is fortunate, there's due process for him. There was no due process for my son" Angelito, said Emily Soriano at a press briefing organised by a local rights group.

Duterte "will be lying down on a good bed, my son is already rotting at the cemetery."

UN Human Rights Chief Volker Turk described the arrest as "a very important step towards seeking accountability for the thousands of victims of killings."

China, however, warned the ICC against "politicisation" and "double standards" in the Duterte case, saying it was "closely monitoring" it.

The high-profile case came with the ICC currently under sanctions from Donald Trump.

The US president is unhappy at the court issuing an arrest warrant for Israeli Prime Minister Benjamin Netanyahu over alleged crimes committed during the Gaza war.

ICC Chief Prosecutor Karim Khan said the fact the arrest warrant had been carried out "is important to victims" and proof that "international law is not as weak as some may think."

'Davao Death Squad'

The Philippines quit the ICC in 2019 on Duterte's instructions.

But the tribunal claims jurisdiction over killings up to then, including ones in the southern city of Davao when Duterte was mayor.

The ICC said in its arrest warrant there were "reasonable grounds to believe" at least 19 people had been murdered in the city by members of the "Davao Death Squad," headed by Duterte.

Additionally, at least 24 people were killed by Philippines police in various locations, judges believe.

On Sunday, Duterte lashed out, labelling ICC investigators "sons of whores" while saying he would "accept" an arrest.

Duterte is still hugely popular among many who supported his quick-fix solutions to crime, and he remains a potent political force.