Human rights groups say Philippine President Rodrigo Duterte and his officials could still be prosecuted at the International Criminal Court for killings in his anti-drug war until his decision to withdraw from the tribunal takes effect after a year.

Presidential spokesman Harry Roque Jr. said Thursday that Duterte's decision was not meant to escape from any accountability but to protest an ICC prosecutor's decision to start examining a complaint against Duterte.

Duterte announced Wednesday that he was withdrawing the Philippine ratification of the Rome Statute "effective immediately." The statute established the tribunal.

Human Rights Watch says the ICC can still prosecute heinous crimes in the Philippines until its withdrawal takes effect a year after Duterte notifies the U.N. secretary-general.