Mr. Acierto, who once led the force’s anti-narcotics division, said he submitted a report to his superiors in December of 2017 warning that two Chinese nationals who knew Mr. Duterte were suspected of involvement with narcotics. One of the two men, named Michael Yang, later became a presidential adviser, although he lost that status last year, Mr. Duterte’s office has confirmed.

But Mr. Duterte and officials in his government have denied that Mr. Yang is involved with drugs. In a speech on Tuesday, Mr. Duterte said Mr. Yang was a telecommunications businessman whose enterprises in the southern Philippines had created many jobs. He accused Mr. Acierto of corruption and various crimes.

“Why would I give importance to his report?” he said. “He should have done his job.”

Mr. Acierto was dismissed from the force last year over a scandal involving illegitimate licenses for assault rifles. He was one of several officers accused of issuing such licenses, for weapons that reportedly ended up in the hands of Communist insurgents. He refused to discuss the matter on Sunday, saying it was being litigated.

Aaron Aquino, the head of the Philippine Drug Enforcement Agency, confirmed that he had received Mr. Acierto’s report on the two Chinese men in 2017 and sent it on to Mr. Duterte’s office. He said Mr. Yang and the other man named in the report did not appear to be on any of the lists of supposed drug suspects, many of them in positions of authority, that Mr. Duterte has made public in the past.

Mr. Acierto, however, said that Mr. Yang was involved with a methamphetamine manufacturing operation in the southern city of Davao as early as 2004. The other man named in the report worked with him, he said. At the time, Mr. Duterte was the mayor of Davao.