President Rodrigo Duterte slammed on Wednesday former President Benigno Aquino III for questioning the effectiveness of his campaign against illegal drugs.

"PNoy said 'apparently nothing happened'. Try to enter into illegal drugs, I will cut your head. You're a fool. Why did you say nothing happened? You're silly," Duterte said in a speech at the Bureau of Internal Revenue in Quezon City.

He claimed some police generals during Aquino's term were involved in illegal drugs, such as the "aide" of former Interior and Local Government Secretary Mar Roxas, and former Gen. Vicente Loot.

Duterte cited the accomplishments of his administration on the war on drugs, including the seizure of illegal drugs.

Aquino, news reports said on Tuesday, said from 1.7 million drug users when he assumed office in 2010, the number went down to 1.3 million during his mid-term before it rose to 1.8 million before he stepped down.

In a statement, Presidential Spokesperson Ernesto Abella cited the gains of the current government, which declared an all out war against narcotics.

"With all due respect to former President Aquino, the results of PRRD's (President Rodrigo Roa Duterte) anti-illegal drug campaign speak for themselves," he said.

"Much ground has been gained in the campaign against hard drug traffickers and violators, but the mission is to end the demand, production, distribution and sale of illegal drugs," Abella stressed.

The Duterte administration’s anti-drug campaign resulted in the "unprecedented voluntary surrender" of more than 1.3 million drug personalities, he said.

Many self-confessed drug users and pushers gave in to authorities amid the increasing number of slain individuals who were allegedly involved in illegal drugs

Abella also cited the 96,703 drug personalities who have been arrested in the first year of the present government compared to 77,810 drug personalities apprehended in the six years of the previous administration.

As to the confiscated illegal drugs, he said that during the first year of the Duterte government, 2,445.80 kilos of shabu was seized compared to the 3,219.07 kilos in the six years of the Aquino government. Celerina Monte/DMS