Malacanang admitted on Thursday the manner on how the war on drugs is being implemented needs to be re-examined following the "not isolated" brutal killings of at least three teenagers allegedly at the hands of policemen.

In a press briefing, Presidential Spokesperson Ernesto Abella said the Palace was dismayed about the "disturbing death" of 14-year-old Reynaldo de Guzman who sustained 31 stab wounds.

The National Bureau of Investigation has been ordered to conduct a thorough investigation and case build-up over the killing of De Guzman whose body was recovered in Gapan, Nueva Ecija, he said.

De Guzman was last seen on August 17 with 19-year old Carl Angelo Arnaiz, who was allegedly killed by the policemen in Caloocan City.

Last month also, 17-year old Kian delos Santos was allegedly shot dead by Caloocan police during their anti-drug campaign.

"We call on authorities to bring the perpetrators of this (De Guzman) suspicious crime to justice," Abella said.

He expressed belief that the leadership of the Philippine National Police is now in the "process of rethinking everything.

"Let’s put it this way. The whole matter is under investigation. In fact, those details that you mentioned are truly suspect. However, we cannot go into any speculation at this stage. It must be properly investigated. And the assurance is there will be no whitewash," he said.

With the killings, he said, "it's not just one isolated event.

"It’s the whole process that we’re undergoing, that we can see that there is a rethinking. A major rethinking going on."

On calls by some quarters to stop the war on drugs, dubbed as "tokhang," Abella said, "the campaign against drugs, illegal drugs is something that the President is entirely committed --- his entire administration.

"However, the manner in which these things are carried out need to really be re-examined," he stressed.

Asked if the Palace is open to calls for a creation of a body focused on extrajudicial killings, he said, "Malacanang is open to all significant and actually workable solutions."

Thousands of drug suspects were reported killed amid the intensified campaign against illegal drugs. Celerina Monte/DMS