The feud between President Ferdinand 'Bongbong' Marcos Jr. and former President Rodrigo Roa Duterte just keeps getting uglier, this time, the latter asking the Chief Executive to undergo drug testing in public to prove that he is not a drug user.

"Set it in Luneta Park, magpakuha siya ng dugo doon [from] independent entity or doctor. Magpakuha rin ako, sige pati ako. Pakuha siya ng blood test," Duterte said during a press briefing in Davao City on Tuesday.

Duterte on Sunday alleged that Marcos was into illegal drugs and was even included in the watchlist of the Philippine Drug Enforcement Agency (PDEA). However, this was belied by the agency, saying that Marcos' name was never on their narco list.

In response, Marcos said Duterte was using fentanyl drug for "a very long time" which he believes the reason behind the latter's behavior.