Malacanang branded on Sunday a retired police officer, who accused President Rodrigo Duterte of ordering the killings in Davao City when he was still a mayor, as a polluted source.

Presidential Spokesperson Ernesto Abella cited the flip-flopping of self-confessed killer Arturo Lascanas regarding his statements on Duterte's supposed creation of the Davao Death Squad.

He noted that Lascanas, who first testified before a Senate inquiry last year on the alleged extrajudicial killings in Davao, denied the existence of DDS.

"Now, the same retired police officer would return to the Senate to expose the DDS," he said.

"Arthur Lascanas has proven himself to be a polluted source and perjured witness. We therefore regard his testimony now as fabricated and unacceptable," Abella stressed.

Lascanas is set to appear on Monday in an inquiry to be conducted by the Senate committee on public order and illegal drugs headed by Senator Panfilo Lacson.

The hearing will be convened after Lascanas recently came out and retracted his initial statement against Duterte.

Lascanas has claimed that he was the leader of the DDS and that Duterte had ordered the killing of a broadcaster critical of him and the bombing of a mosque, among others. Celerina Monte/DMS