Philippine Vice President Sara Duterte gave a speech to her supporters in Australia to call for the release of her father Rodrigo Duterte, who is in custody over his war on drugs.

Sara urged the loyalists to convince Australian authorities to probe the alleged illegal detention of her dad, who was arrested in March by the International Criminal Court (ICC) for alleged crimes against humanity.

Speaking at the Parliament Gardens in Melbourne on Sunday, the younger Duterte said: 'You convince the government of Australia — because Australia is a member of the ICC — to look into the case of President Duterte and the injustice that he is receiving, that he has been getting from the ICC.

'You talk to the government of Australia. Come together, sit down, come up with a position paper. Bring his case to the local Australian media, bring his case to the global community through your social media accounts.'

Sara, who herself was impeached by the House of Representatives over alleged corruption, also slammed her political rival, Philippine President Ferdinand Marcos Jr., for 'having no plan or vision' for the country.

The rally was attended by dozens of Duterte fanatics, who flocked to take selfies with the Vice President after her speech.

Overseas Filipino workers, most of whom rely on social media for news, are among the biggest supporters of the powerful Duterte family who are known for weaponising online platforms to unleash torrents of disinformation.

Rodrigo 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.

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.

He is now incarcerated at The Hague in the Netherlands. His lawyers are seeking his interim release to another country, citing old age.

The request to the ICC pre-trial chamber read: 'Mr Duterte is no longer the President of the Philippines, and does not command the same influence or power he is said to have abused during the period of the alleged crimes.'