Philippine President Rodrigo Duterte has showered praise on police officers, who carried out a series of raids that killed at least 32 suspected drug offenders - the bloodiest night in the ongoing drug war - calling it "beautiful".

"That's beautiful. If we can only kill 32 every day, then maybe we can reduce what ails this country," Duterte said in a mix of Filipino and English on Wednesday, during a gathering at the Malacanang presidential palace in the capital, Manila.

According to senior police officer Romeo M Caramat Jr, during 67 operations in various parts of Bulacan province on Tuesday, police killed 32 suspects and arrested 109 others.

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Police also claimed to have seized more than 200 grams of methamphetamine, 786 grams of cannabis, assorted firearms, grenades and ammunition.

Bulacan, a province of about 3.29 million people, has recorded numerous arrests and killings of drug suspects in recent months, police records showed.

Duterte has vowed to protect police who kill drug suspects under suspicious circumstances.

"Drugs is eating our country. It really takes a toll in our country, whether you are the victim or the criminal. If you do not do anything drastic...that's the problem," Duterte said on Wednesday.

Government figures show that since Duterte took office last year up to July 26, an estimated 3,451 "drug personalities" have been killed in gun battles with police.

'Police collusion'

More than 2,000 others died in drug-related homicides, including attacks by motorcycle-riding masked gunmen and other assaults. Another 8,200 homicide cases were under investigation, police said.

Despite warnings by human rights groups that Duterte may be overseeing a crime against humanity, the leader remains widely popular in the Philippines.

He won a landslide victory in presidential elections last year after promising an unprecedented war on drugs.

At the event in Manila on Wednesday, Duterte said that as soon as he became president in 2016, he found out that police generals and other officers were also involved in the drug smuggling operation.

"So, how can I finish it...even the United States cannot solve their own [drug] problem," Duterte said. "But I will finish it. I will just kill all of them."

Meanwhile, in neighbouring Indonesia, Amnesty International said on Wednesday police were taking a leaf out of Duterte's "war on drugs" and have killed 60 suspected drug dealers so far this year, compared to 18 in all of 2016.