THE HAGUE/MANILA - Former Philippine president Rodrigo Duterte did not attend in person his initial appearance hearing at the International Criminal Court (ICC) on Friday afternoon but appeared via video link.

The initial hearing, which was scheduled to begin at 2 pm local time in the ICC's Pre-Trial Chamber I, was delayed for some 30 minutes. The Chamber is composed of three judges, presided over by Judge Iulia Antoanella Motoc.

Motoc explained that the former president was allowed to follow the hearing remotely from the ICC Detention Center because he had just made a long flight journey involving a considerable time difference. The court proceeded to confirm his identity.

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Duterte's lawyer, Salvador Medialdea, said at The Hague-based court that his client had been "abducted from his country".

"He was summarily transported to The Hague. To us lawyers, this would be called an extrajudicial rendition. To the less legally inclined, it's a pure and simple kidnapping," he said.

He also said that Duterte was experiencing "debilitating medical issues".

"Other than to identify himself, my client is not able to contribute anything to this hearing," he stated.

At the end of Friday's hearing, the court scheduled the confirmation of charges hearing to commence on Sept 23 this year.

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The confirmation of charges procedure determines whether sufficient evidence exists to establish substantial grounds that the accused committed the alleged crimes. If the charges are wholly or partially upheld, the case will proceed to a Trial Chamber for the next phase, "the trial", according to ICC.

Duterte, 79, was detained on Tuesday morning upon his return to Manila from an overseas trip, following an arrest warrant issued by the ICC over his controversial "war on drugs" campaign, a move he has challenged.

He was subsequently transferred to ICC custody on Wednesday after being flown from Manila to the Netherlands.

The Philippines' decision to detain Duterte and transfer him to The Hague has sparked significant controversy, prompting his supporters to hold rallies across multiple cities in recent days.

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Duterte's supporters gathered outside the Supreme Court in the Philippine capital on Thursday afternoon, lighting candles in hopes of Duterte's return to the Philippines.

On Thursday evening, supporters held a prayer vigil outside Duterte's house in Davao city, a southern metropolis, conveying their message of support for the former president.

On Wednesday evening, over 100 supporters gathered for a prayer rally in the City of San Fernando in Pampanga province. They carried placards and banners with Duterte's face and the words "Justice for PRRD (President Rodrigo Roa Duterte)" and held a motorcade-style rally in the city, local media reported.

Veronica Duterte, daughter of the former president, on Friday called on Filipinos to "light a candle" and stand in solidarity.

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"I am calling unto you, not as his supporters, but as Filipinos, to stand for what is right and light a candle, whether you are in the Philippines or abroad. Let us be one in prayer and one in upholding our rights to this sovereignty," she wrote in an Instagram story.

Philippine GMA Network reported that Duterte's legal team will be pushing for his temporary release from the ICC, as his team holds the belief that there was no reason to detain him during his impending trial.