The Philippines vowed on Friday to stop the chief enforcer of ex-president Rodrigo Duterte's drug war from fleeing the country to evade an International Criminal Court (ICC) arrest warrant.

Fugitive senator Ronald "Bato" Dela Rosa, who barely escaped arrest on Monday when he sought refuge in the senate building, left unannounced for an unknown location on Thursday.

Justice Secretary Fredderick Vida confirmed Manila has received the arrest warrant for Dela Rosa from the ICC, but was waiting for the Philippine Supreme Court to resolve the senator's petition challenging its legality.

"The Department of Justice will treat any attempt of Senator Bato Dela Rosa to leave the country as a mockery of justice," Vida said.

Law enforcers and border officials were instructed "that if Senator Bato Dela Rosa were to try to leave the country, that the appropriate arrest should be made".

The ICC on Monday unsealed an arrest warrant against Dela Rosa, 64, accusing him along with Duterte and other "co-perpetrators" of the "crime against humanity of murder".

Senate president Alan Peter Cayetano prevented government agents from arresting his political ally Dela Rosa on Monday, giving him refuge in the building.

Dela Rosa served as national police chief from 2016 to 2018 during the early phase of Duterte's anti-drug campaign and was elected to two successive six-year terms in the Senate in 2019 after retiring from the force.

The crackdown left thousands dead, many of them drug users and low-level narcotics peddlers, according to human rights monitors.

Dela Rosa has asked the Supreme Court to stop the government from enforcing the ICC arrest warrant and expressing preference to stand trial in a Philippine court if he were charged.

His boss Duterte was arrested in March last year, flown to the Netherlands on the same day, and is being detained in The Hague awaiting trial. (AFP)


Edited by Aaron Tam