MANILA – An international human rights group slammed the ouster of Senator Leila de Lima as chairman of a senate committee probing cases of extrajudicial killings connected to President Rodrigo Duterte’s war on drugs.

New York-based Human Rights Watch (HRW) said the Senate should seek de Lima’s reinstatement as chair of the Senate committee on Justice and Human Rights.

“The Senate vote to remove the chair of the Committee on Justice and Human Rights is a craven attempt to derail accountability for the appalling death toll from President Duterte's abusive ‘war on drugs,’” said Phelim Kine, deputy Asia director at Human Rights Watch.

“The Senate is imperiling the Philippine public by covering up allegations of state-sanctioned murder rather than exposing them,” Kine added.

De Lima, erstwhile chair of the Senate committee on Justice and Human Rights, earlier launched a probe into the drug-related deaths in the country which have caught the attention of the international community.

Before she was ousted, de Lima was able to present witness Edgar Matobato, a self-confessed former member of the Davao Death Squad who claimed he carried out killings on orders of Duterte, the city’s long-time mayor.

Matobato’s allegations riled the administration, and de Lima believes Duterte was behind her ouster.

READ: De Lima laments Senate didn't assert independence

Breaking up his silence on Matobato’s allegations, Duterte noted that perjury is a serious crime. Reacting on de Lima’s ouster, he said he does not meddle in the affairs of the legislative branch.

Over 1,000 drug suspects have been killed since Duterte assumed office on July, police data show, and human rights groups are calling for a thorough investigation amid allegations that law enforcers are ignoring due process and abusing their power.

“The Philippine Senate has a duty to promote accountability for the thousands of victims of this ‘war on drugs,’ rather than siding with those advocating summary killings as law enforcement,” Kine said.

“Opposition to an impartial investigation into these killings only intensifies the spotlight on Duterte and his administration’s disregard for basic human rights protections for all Filipinos,” he added.