MANILA - Outgoing Philippine National Police chief Ronald "Bato" Dela Rosa should be held accountable for thousands of killings under the war on drugs, Human Rights Watch said Wednesday.

Carlos Conde, Philippine researcher for the international watchdog, said Dela Rosa will leave behind a "sordid human rights record" when he retires Thursday.

"He will leave behind a police force with a sordid human rights record unmatched since the Marcos dictatorship," Conde said in a statement.

"That campaign has targeted mainly urban slum dwellers and resulted in the deaths of more than 12,000 men, women and children by police and police-backed vigilantes," he claimed.

Data from the Philippine Drug Enforcement Agency showed that as of March 20, 2018, 4,075 drug-linked individuals have been killed in 91,704 anti-illegal drug operations since July 2016.

The police's "Real Numbers" further showed that out of the total 2,467 drug related homicide incidents recorded, 1,752 are still under investigation, while 715 have been solved.

But Conde said these numbers are flawed, as independent analyses show. Human Rights Watch research, he added, found out many drug war killings were summary executions with planted evidence.

"Police statistics, which independent analyses have derided featuring 'flawed and inflated numbers,' reflect a lower death toll of more than 4,000 killings by police in anti-drug operations," he said.

Conde added that the International Criminal Court (ICC) has begun examination into the killings with a "growing momentum" for a separate probe inside the United Nations.

"These developments suggest that sooner or later, Dela Rosa may be held to account for the bloody campaign he so zealously endorsed," he said.

ACCOMPLISHMENTS AS PNP CHIEF

Dela Rosa earlier said that he considers the drug war as one of his accomplishments as PNP chief. He maintained that killings linked to the drug war are not state-sponsored.

"Masasabi ko talaga na isa ‘yun sa malaking accomplishments natin—ang no holds barred response to the drug problem in the Philippines," he said, telling his successor to "continue the fight."

Throughout Dela Rosa's tenure, the police have maintained that the people who were killed in anti-illegal drug operations "fought back" against arresting officers.

The outgoing PNP chief admitted there are still police "scalawags" but they are doing their best to cleanse the organization.

Metro Manila's Police Director Oscar Albayalde will replace Dela Rosa who will step down Thursday. The incoming police chief said the drug war will continue under his watch.