MANILA - The Philippines' top police officer and chief enforcer of President Rodrigo Duterte's brutal drug war stepped down on Monday (Oct 14) amid allegations that he harboured a number of corrupt policemen under his watch six years ago.

General Oscar Albayalde relinquished his post as head of the 170,000-strong Philippine National Police (PNP) just weeks before his retirement. He is set to retire on Nov 8, when he turns 56.

"After careful thought and deliberation, I have come to the decision to relinquish my post as chief, PNP, effective today and go on non-duty status," he announced at a flag-raising event at the PNP's main camp in Manila.

Gen Albayalde has been accused of protecting 13 "ninja cops" - policemen he supervised as a provincial commander in 2013 who were said to have made millions selling crystal meth they confiscated in a drug raid and setting the top suspect, a Chinese, free.

Two retired senior police officers accused him in Senate hearings last week of profiting off this scam.

The scandal strikes at the very heart of Mr Duterte's crackdown on the narcotics trade.

Human rights groups have accused police of executing thousands of drug suspects and staging crime scenes.

But Mr Duterte has stood by the police force, insisting those killed resisted arrest.

Gen Albayalde, a strict disciplinarian who had been in charge of Metro Manila, where the majority of the thousands of drug war killings have occurred, was appointed PNP chief last year.

He vowed at the time to pursue the bloody war on drugs, and build on the "remarkable accomplishments" of his predecessor, now Senator Ronald de la Rosa.

The Senate had been probing irregularities in the early release of prisoners, when charges of corruption against Gen Albayalde surfaced.

Among the incidents that came up was a drug raid in 2013 in the town of Mexico, in Pampanga province, north of Manila.

Internal investigations revealed that 13 policemen under Gen Albayalde, who was then Pampanga police chief, seized more than 200kg of crystal meth and arrested a Chinese financier, Johnson Lee.

But they later declared in their reports that they confiscated only 38kg, according to investigators. The other 162kg they allegedly did not turn over was estimated to be worth 648 million pesos (S$17 million).

They also purportedly released Lee after he paid them millions, and produced a different "suspect", Ding Wenkun.

These anomalies set off a probe.

A retired senior police officer, Mr Benjamin Magalong, who was at the time chief of the PNP's Criminal Investigation and Detection Group (CIDG), told senators all members of the raiding team and Gen Albayalde were later found to have bought new sport utility vehicles for themselves.

An order eventually went out for the team to be dismissed. Gen Albayalde was relieved of his post. But far from being disgraced, he was appointed regional director of Metro Manila in 2016.

That year, he supposedly called Philippine Drug Enforcement Agency chief Aaron Aquino to ask him to not implement the dismissal order against the 13 policemen involved in the 2013 raid.

None of them were dismissed, and some were even promoted.

Mr Aquino told senators he asked Gen Albayalde why the policemen should not be suspended. Gen Albayalde replied: "Because they're my people."

Former CIDG deputy director Rudy Lacatin also testified that Gen Albayalde told him he skimmed just "a little" off the drug loot in the 2013 raid.

Gen Albayalde said these allegations were all hearsay and innuendos. He suggested "everybody is ganging up on me", as factions in the police force manoeuvre to have him replaced as police chief with their own candidates.

He said he has never been charged over anomalies in the 2013 drug raid, and that the cases against the raiding team were dismissed "for insufficiency of evidence" and "lack of probable cause", not because he intervened.

Mr Duterte's spokesman Salvador Panelo issued a sympathetic reply to Gen Albayalde's decision to step down.

"Perhaps he has had enough of the innuendos," he said.