MANILA - Malacañang on Thursday said there is no need for President Rodrigo Duterte to undergo a drug test, after being challenged yet again by opposition senator Antonio Trillanes IV.

"Hindi kailangan. Eh talaga namang — look at this person, this president. Malakas. Sinasabi niya naman sa atin kung ano ang diperensya niya eh,” Presidential Spokesman Salvador Panelo said in Palace press briefing.

Trillanes challenged Duterte to just undergo a drug test after the latter “joked” that he takes marijuana to deal with his hectic schedule.

"Duterte is desperately trying to contain the damage of his admission about marijuana use by saying it is just a joke. Too late! Bistado na siya na isa rin pala siyang durugista. Now, if he really wants to clear himself, I am again calling on him to take a drug test,” Trillanes said in a statement Thursday.

Duterte, drawing flak for his “joke,” said he only wanted to "lighten a dull moment” everytime he speaks in public, which is why he sometimes utter “ridiculous” statements.

• Joke only: Duterte says he takes marijuana
• Palace: Duterte entitled to make jokes

"If it is too ridiculous, it must be a joke,” Duterte said in a speech during the awarding ceremonies for the 2017 Presidential Award for Child-Friendly Municipalities and Cities (PACFMC) in Malacañang on Wednesday.

Duterte has waged a controversial war on drugs, mostly targeting users and traders of shabu, the drug of choice for many addicts in the Philippines.

While the President is against synthetic substances such as shabu, he is open to the use of marijuana for medical purposes.

• Duterte, pabor sa medical marijuana, ayon sa Palasyo

The New York-based Human Rights Watch said Duterte’s marijuana joke is not funny, considering the soaring number of deaths linked to his war on drugs.