THE HAGUE, June 14 (AFP) - The International Criminal Court's chief prosecutor on Monday (Jun 14) sought a full investigation into crimes against humanity during the Philippines' "war on drugs", in one of her last acts before stepping down this week.

Fatou Bensouda asked judges at the world's only permanent war crimes court to authorise a probe into allegations that police unlawfully killed as many as tens of thousands of civilians between 2016 and 2019.

The Philippines left the ICC in 2019 after the court launched a preliminary examination into President Rodrigo Duterte's drug crackdown, but Bensouda said it could still investigate crimes committed while Manila was a member.

"I have determined that there is a reasonable basis to believe that the crime against humanity of murder has been committed .. in the context of the government of Philippines 'war on drugs' campaign," Bensouda said in a statement.

"The available information indicates that members of the Philippine National Police, and others acting in concert with them, have unlawfully killed between several thousand and tens of thousands of civilians" during the period under investigation.

Gambian lawyer Bensouda, whose term of office ends on Tuesday, said that "any authorised investigation in the Philippines will fall to my able successor, Mr Karim Khan, to take forward".

Britain's Khan will be sworn in on Wednesday with a host of other challenges in his inbox including a probe into Israel and the Palestinian territories.

Duterte's drug crackdown has drawn international censure and prompted the ICC to launch its preliminary probe three years ago.

The crackdown is Duterte's signature policy initiative and he defends it fiercely, especially from critics like Western leaders and institutions which he says do not care about his country.

He was elected in 2016 on a campaign promise to get rid of the Philippines' drug problem, openly ordering police to kill drug suspects if their lives are in danger.

More than 6,000 people have been killed in over 200,000 anti-drug operations conducted since July 2016, according to official data. Human rights groups estimate the number of dead could be several times higher.