China is closely monitoring the prosecution of former Philippine President Rodrigo Duterte after he was arrested for alleged crimes against humanity based on the warrant issued by the International Criminal Court (ICC).

"This is an important sudden incident. China has noted the news and is closely following how this might develop," China's Foreign Ministry spokesperson Mao Ning told reporters in a press conference in Beijing a day after Duterte's arrest.

Mao noted that the ICC should also "prevent politicization or double standards".

"I would like to reiterate China’s consistent view that the International Criminal Court should strictly follow the principle of complementarity, exercise its functions and powers prudently in accordance with the law and prevent politicization or double standards," she said.

The relationship between the Philippines and China significantly improved during the term of the former president after the tension in the West Philippines Sea heightened since the 2012 standoff in Scarborough Shoal.

Duterte, who was immediately arrested upon his arrival from Hong Kong on Monday and flown to the Netherlands on the same day, is now placed under the custody of the ICC. Robina Asido/DMS