MANILA - President Rodrigo Duterte on Thursday explained the darkening of his skin, something that his critic, communist leader Jose Ma. Sison, had noticed and alleged to be caused by a serious illness.

"Look at an ideologue, look at what he is now. Ang istoryahan imbes na unsay kaayuhan sa kalihukan, sige nang kinuan ang akong nawong daw nasunog, itom," Duterte said in a speech in Davao City.

(Look at an ideologue, look at what he is now. Instead of discussing what's good for the group, he chose to focus on my appearance, he says my face is darkening.)

"Alang-alang di muitum sigeng suroy bukid, saka-panaog. Nya di man kog gamit anang sa babayi na, sa babayi na maglanay. Sa eleksyon ko pa ito. He played into may hands, kanang tirada."

(How could it not darken if I go up and down mountains. I don't use women's [cosmetics], it melts. It started during the elections. He played into my hands, that's the strategy.)

The President also claimed that Sison “played into my hands” and bought his claims about his health.

“Ganyan naman ako magsalita. Doon iyung lumabas na ‘O ang lagay ko, sabihan niyo na lumipad ako and I’m suffering from kidney failure, tapos ang aking cancer kumalat na… na si Duterte medyo ano na sumakay sa chopper na nakapikit na. Kinuha din agad ni Sison na bugok,” he said.

Presidential spokesman Harry Roque earlier claimed that Duterte's darker face may have been caused by the President "not wearing powder."

"I don’t know maybe he was just not wearing powder. Normally the President wearing powder; maybe there was just a photo taken of him without powder ‘no. So I don’t see anything extraordinarily different from the color of the President’s face ‘no," he said.

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Sison, in a Facebook post Sunday, claimed that Duterte fell seriously ill recently. He showed a photo of the President supposedly taken from a Lex Talionis event last August 18.

“Those who saw him reported that the darkness of his face had become aggravated from its appearance the other day and that his walk and handshake had become more unstable,” Sison said.

“The latest report (still to be verified or negated) is that Duterte has gone into coma since the afternoon or evening of today, Sunday, August 19,” he added.

Duterte himself debunked Sison’s claim, and went live on Facebook on Monday evening to show he was in good health. He also graced the League of Municipalities of the Philippines Visayas Island Cluster Conference in Cebu City on Tuesday where he spoke for almost two hours.

• Duterte tells Sison: Matagal pa ako

Questions on the health of the President, now 73, are being raised from time to time by his critics. But the Palace said there was no need for it to release a regular bulletin on the President’s health.

The President himself has raised the possibility of not ending his term, fueling speculations about his health.

Duterte and Sison's ties soured after the President cancelled peace talks with the communists.

The government is now seeking to hold localized peace talks with communist rebels, in what analysts said was an attempt by the government to make Sison irrelevant. - with a report from Madonna Timbal-Senajon, ABS-CBN News