Philippine officials today probed the arrest of drugs war madman Rodrigo Duterte who is now detained in the Netherlands.

Footage shows Senators Imee Marcos and Ronald dela Rosa, both staunch Duterte allies, arriving at the Senate in Metro Manila on April 3.

The probe was launched by the Senate panel on foreign relations, which is headed by presidential sister Imee.

Imee Marcos is an stalwart ally of the Duterte clan and is the elder sister of Philippine President Ferdinand Marcos Jr., who is accused of permitting Duterte's arrest by the International Criminal Court. Despite denying claims of a sibling feud, she has repeatedly opposed her younger brother in clashes between the two powerful political families.

The probe also marks the first appearance of Ronald at the Senate since Duterte's arrest. He had also been implicated by the International Criminal Court in alleged crimes against humanity during his term as former national police chief.

He said: 'I will try to apply for a Schengen visa. If I will be issued one, then maybe if there is an opportunity ... I hope to visit former president Duterte before the elections ... maybe before or after the elections, win or lose.

'I will wear a wig in The Hague so I won't be recognised.'

Duterte - who once boasted of throwing a rival out of a helicopter to his death - was arrested on March 11 morning at the Ninoy Aquino International Airport on a warrant issued by the ICC in the Hague.

He had initially refused to disembark the plane upon arrest, telling officials: 'You will just have to kill me. I refuse if you will just ally with the whites.'

He was later seen boarding a police vehicle with his wife Honeylet Avancena and daughter Veronica. He had returned to the country on Cathay Pacific flight CX907 after meeting with overseas Filipino workers in Hong Kong a day earlier.

Philippine President Ferdinand Marcos Jr., a former ally and now political rival of the influential Duterte family, defended the government's role in the strongman's arrest.

He said: 'Interpol asked for help and we obliged because we have commitments to Interpol which we have to fulfil. If we don't do that, they will no longer help us with other cases involving Filipino fugitives abroad. We cannot say no to Interpol when they ask us to catch a wanted individual.'

Duterte is the architect of the country's notorious bloody war on drugs, which police claimed saw more than 6,000 drug suspects killed. However, human rights groups said the alleged extrajudicial executions reached up to 30,000.

In 2018, Duterte withdrew the Philippines from the ICC after it began investigating alleged human rights abuses linked to his war on drugs. He had argued that the ICC had no jurisdiction over the Philippines and accused it of being biased.

The ICC has set the confirmation of charges hearing for Duterte on September 23.