Philippine President Rodrigo Duterte has defended his kiss on the lips of a married Filipino woman in South Korea, and said he will resign if enough women are offended and sign a petition calling for him to step down.

Duterte has described Sunday's kiss as "pure showbiz" intended to entertain a crowd of Filipino expatriates. Feminists called it his "perverted way" of taunting female critics who are angered by frequent derogatory comments, some of a sexual nature.

"If there are enough women to ... well I think if all women here would sign a petition for me to resign, I will resign," Duterte told a media briefing around midnight on Tuesday upon his return from an official visit to South Korea.