President Rodrigo Duterte admitted on Wednesday he ordered retired General Dionisio Santiago to quit as head of the Dangerous Drugs Board because he was "offended" by what the former official had said.

In a press conference at the airport before leaving for Vietnam, Duterte said Santiago could have directly told him that putting up community-based rehabilitation centers was the better approach than having a huge rehabilitation center inside a military camp in Nueva Ecija.

"He (Santiago) uttered words that 'it (mega rehabilitation center) is a waste of money,' that 'it is not the right approach.' You know, you saw him in the previous administration. He was there. Why did he not make it?," he said.

Santiago headed the Philippine Drug Enforcement Agency during the Arroyo administration.

"So he came up with a very incongruous statement that I was offended. He could have asked me for an audience and then tell me all about it," Duterte said.

Duerte said he appointed Santiago as DDB chairman not to issue statements to the press but to let him know what he could do to address the problem.

"But you do not go open to the press and start to blabber," he said.

Santiago submitted his irrevocable resignation after Executive Secretary Salvador Medialdea asked him to do so on the order of the President.

Duterte has yet to appoint Santiago's replacement. Celerina Monte/DMS