President Rodrigo Duterte on Thursday said the drug problem in the country is "kind of under control".

"The drug (problem) is kind of under control now but I need to really reduce it," Duterte said in his speech during senatorial candidate Francis Tolentino's birthday celebration in Tagaytay City.

Duterte admitted he had a mistake in thinking he can solve the drug problem in the whole Philippines like what he did in Davao City while he was mayor.

"I had a mistake ... because I thought I could fix it just like (in) Davao (City). Simple, I really killed them. We can't do anything. They fight back," Duterte said.

He said it's impossible to finish the problem within six years because of involvement of some government officials to drugs.

"If (the situation) is like this, I can't really fulfill my promise to throw away drugs in six years. Impossible," said Duterte.

Duterte again warned big personalities and groups involved in drugs that he will kill them.

"If you are big time, I can't forgive you. In front of human rights (groups), I slit your throat," he said.

Duterte said he is ready to go to prison and even face international tribunal to take responsibility on the alleged 5,000 people killed in the anti-illegal drug operations.

"If the police said they killed 4,000, official recorded. That's mine. And I will go to prison for it," Duterte said. "I will answer for everything," he added.

Duterte said he is not sorry for his action towards his war on drugs.

"Am I sorry for it? I'm not. Will I ever do it again for the coming years, I will. Until I finish everything or they finish me (first)," he said.

Recent data from the Philippine Drug Agency (PDEA) showed that from July 1, 2016 when the administration implemented the anti-drug campaign to November 30 of this year, 5,050 "drug personalities" died during police operations. Most casualties were reported killed as they resisted arrest. Ella Dionisio/DMS