MANILA (Reuters) - Activists and opponents of Philippine leader Rodrigo Duterte called for legal action against him on Friday after he appeared to admit responsibility for extrajudicial killings, in remarks his spokesman said were “playful” and misinterpreted.

FILE PHOTO: President Rodrigo Duterte speaks after his arrival, from a visit in Israel and Jordan at Davao International airport in Davao City in southern Philippines, September 8, 2018. REUTERS/Lean Daval Jr.

The mercurial president is the subject of two complaints before the International Criminal Court (ICC) that accuse him of crimes against humanity over thousands of deaths during his bloody anti-narcotics campaign.

Duterte, known for rambling, at times perplexing speeches, apparently conceded that summary executions had taken place during his war on drugs, something he has vigorously denied when accused by rights groups and critics.

During a routine speech at an oath-taking ceremony for bureaucrats on Thursday, he chided unspecified critics in a tirade about which the context was not clear.

“What is my sin? Did I steal, even one peso? Did I prosecute somebody whom I jailed,” Duterte said. “My only sin is the extrajudicial killing,” he said, without elaborating.

Police have killed more than 4,800 people since Duterte took office in July 2016 and unleashed his anti-drug crackdown.

The government denies activists’ allegations that police are exterminating drug users, and say those killed were all dealers who had resisted arrest.

Police also deny involvement in several thousand other street killings of addicts, blaming the largely unsolved murders on criminals.

U.N. special rapporteur on extrajudicial killings, Agnes Callamard, called Duterte’s remark “extraordinary” and said he had effectively admitted to “imposing unthinkable sufferings on thousands of families, emboldening corrupt policing and destroying the rule of law”.

Opposition Senator Risa Hontiveros said the comment “establishes his clear and direct accountability for the killings”, while Minar Pimple of London-based Amnesty International, said the ICC should take note, and that an international investigation was urgently required.

Presidential spokesman Harry Roque said Duterte was being facetious and was hitting back at opponents.

“That’s the president being himself, being playful, highlighting the point that he is not corrupt,” Roque said on radio.

But Brad Adams, Asia director of New York-based Human Rights Watch, said Duterte’s remark “should prod the ICC to speed up its consideration of the cases filed against him”.

The ICC launched a preliminary examination this year, prompting Duterte to unilaterally cancel the Philippines’ membership of the ICC’s founding treaty, saying it sought to portray him as a “ruthless and heartless violator of human rights”.

Legal experts say the withdrawal was pointless because the ICC’s jurisdiction can apply retroactively.

In the same speech, Duterte joked that a tight supply of cheap rice was caused by rehabilitated drug addicts who had regained their appetite.