Philippines President Rodrigo Duterte has sought to reassure soldiers who might be accused of committing abuses under martial law, and jokingly said that if any of them were to rape three women, he would personally claim responsibility for it.

Duterte is notorious for comments often deemed offensive and intended the remark as a joke, reiterating that only he would be liable for any backlash over military rule on southern Mindanao island. He has, however, said he will not tolerate abuses.

"If you go down, I go down. But for this martial law and the consequences of martial law and the ramifications of martial law, I and I alone would be responsible, just do your job, I will take care of the rest," Duterte said on Friday, according to a president's office transcript.

"I'll imprison you myself," he said, referring to any soldiers who commit violations, then he joked: "If you had raped three, I will admit it, that's on me."

Duterte made the remark in a speech to soldiers on Mindanao island, where he imposed martial law on Tuesday to try to crush Islamic State-linked rebels, who have been battling the military after laying siege to a southern city.

The comment sparked criticism on social media and Chelsea Clinton, daughter of former U.S. president Bill Clinton and presidential candidate Hillary Clinton, called Duterte "a murderous thug with no regard for human rights."

"It's important to keep pointing that out & that rape is never a joke," Clinton tweeted.

It was not the first time Duterte has made a joke about rape. He caused outrage in the lead-up to his presidential election win last year when he recalled a 1989 prison riot in which an Australian missionary was killed, and inmates had lined up to rape her.

In what was intended as a joke, Duterte said the victim was beautiful and as mayor of Davao city where the riot took place, he should have been first in line. He later apologized and said he did not intend disrespect to women or rape victims.

Duterte is known for his informal, no-nonsense style and his speeches are often loaded with profanity, threats and jokes about taboo subjects, which offend some, but are taken lightly by many Filipinos.

He also joked on Friday that he would join soldiers in the fight against extremists if he could, but he had arthritis.