VICE PRESIDENT Sara Duterte-Carpio on Thursday said allowing prosecutors from the International Criminal Court (ICC) to investigate crimes committed in his father’s deadly war on drugs is illegal and undermines the Philippine justice system.

“To allow ICC prosecutors to investigate alleged crimes that are now under the exclusive jurisdiction of our prosecutors and our courts is not only patently unconstitutional but effectively belittles and degrades our legal institutions,” she said in a statement.

Ms. Duterte-Carpio’s remarks — the first time she spoke about the issue openly — come on the heels of a congressional push for the government of President Ferdinand R. Marcos, Jr. to cooperate with the ICC probe.

The ICC investigation covers crimes allegedly committed in Davao City from November 2011 to June 2016 when ex-President Rodrigo R. Duterte was its mayor, as well as drug killings during his presidency.

Meanwhile, a global human rights coalition said Mr. Marcos should heed the call of a United Nations (UN) human rights expert to abolish the country’s anti-communist task force to address impunity in the country.

In a statement, the International Coalition for Human Rights in the Philippines cited cases of harassment and persecution against activists and environmental defenders by the National Task Force to End Local Communist Armed Conflict (NTF-ELCAC).

“We strongly endorse his call to stop the attacks against environmental defenders including civil society and indigenous peoples’ organizations,” ICHRP Chairman Peter Murphy said, referring to UN Special Rapporteur on human rights and climate change Ian Fry.

The NTF-ELCAC did not immediately reply to a Facebook Messenger chat seeking comment.

On Nov. 15, Mr. Fry said he was alarmed by reports of the task force and the military tagging members of indigenous communities as communists.

“There are clearly people who have suffered dramatically as a consequence of the persecution of environmental human rights defenders,” he told a news briefing.

Last week, Senator and former national police chief Ronald M. dela Rosa described Mr. Fry as “misinformed,” saying he was not aware of the government’s side and efforts to combat the communist movement in the Philippines.

Justice Secretary Jesus Crispin C. Remulla earlier said the UN should not interfere in the government’s anti-insurgency drive.

The Philippines has remained the deadliest country in Asia for environmental and land defenders for a decade, according to human rights watchdog Global Witness.

The group noted that 11 of the 16 killings in the region last year occurred in the Philippines.

In a September report, Global Witness said the country was the fifth-deadliest for environmentalists in the world last year.

“ICHRP welcomes the long overdue agreement by President Ferdinand R. Marcos, Jr.’s administration to allow UN Human Rights Council Special Rapporteurs to visit the Philippines,” Mr. Murphy said, citing six years of blocking by the previous administration.

Meanwhile, Senator Robin C. Padilla asked the government to end discussions about Philippine cooperation in the International Criminal Court’s (ICC) investigation of ex-President Rodrigo R. Duterte’s deadly war on drugs.

“Such an issue should have already ended when the Philippines withdrew as a member of the ICC during the administration of former President Rodrigo Roa Duterte,” he said in a statement. “I wish to put a definite end to it now because it will only bring confusion to our people.”

Mr. Padilla backed Mr. Marcos’s decision to stop engaging with the ICC after the court denied the Philippines’ plea to halt its probe of the anti-illegal drug campaign.

Mr. Duterte withdrew Philippine membership in the ICC in 2018.

Manila Rep. Bienvenido M. Abante, Jr. and Party-List Rep. France L. Castro earlier filed separate House resolutions urging the state to cooperate with the ICC probe.

In February, Mr. Padilla filed a resolution urging the Senate to declare its “unequivocal defense” of Mr. Duterte, citing a functional local justice system. Pampanga Rep. and former President Gloria Macapagal Arroyo filed a similar resolution at the House of Representatives.

The ICC in January reopened its probe of the previous government’s anti-illegal drug campaign, saying it was not satisfied with Philippine efforts to probe human rights abuses during the period.

The court rejected a Philippine plea to suspend its probe of the drug war in July, paving the way for the ICC prosecutor to later indict and order the arrest of local officials who aided the campaign.

On Wednesday, Albay Rep. Edcel C. Lagman said the ICC could probe human rights abuses since these happened while the Philippines was still a member of the ICC.

The Philippine Justice department has said the international tribunal is undermining the Philippine government’s sovereignty by continuing its probe of Mr. Duterte’s drug war.

The Philippines has accepted 200 recommendations from the United Nations Human Rights Council, including investigating extralegal killings and protecting journalists and activists.

The government estimates that at least 6,117 suspected drug dealers were killed in police operations. Human Rights groups say as many as 30,000 suspects died. — John Victor D. Ordonez and Kyle Aristophere T. Atienza