MANILA - A former Colombian president who launched Colombia's bloody narcotics crackdown and battled drug kingpin Pablo Escobar, has some advice for President Duterte: Taking a hard line against drug suspects is not the way to win the war on drugs.

"Throwing more soldiers and police at the drug users is not just a waste of money but also can actually make the problem worse. Locking up nonviolent offenders and drug users almost always backfires, instead strengthening organized crime," former president Cesar Gaviria wrote in a New York Times opinion column.

Gaviria said he learned this "the hard way" because Colombia, one of the world’s primary suppliers of cocaine, waged war on drugs at an "enormous cost" by pouring billions of dollars to abolish drug cartels, destroying drug crops and jailing every drug pusher in sight.

All these measures, he said, only resulted to "new problems," including the slaughter of tens of thousands of people; the assassination of their brightest officials, journalists and law enforcers; the corruption of politicians tempted with drug payoffs; and the spread of Colombian drugs to neighboring countries.

In his column, Gaviria recommended instead that the Philippines strengthen public health programs, safeguard human rights and focus on economic development -- no matter how popular the drug war may be.

"Taking a hard line against criminals is always popular for politicians. I was also seduced into taking a tough stance on drugs during my time as president. The polls suggest that Mr. Duterte’s war on drugs is equally popular," he said.

"But he will find that it is unwinnable. I also discovered that the human costs were enormous. We could not win the war on drugs through killing petty criminals and addicts. We started making positive impacts only when we changed tack, designating drugs as a social problem and not a military one."

MILITARY JOINS DRUG WAR

Duterte, he said, must also drop plans to issue an executive order that would allow the military to come after drug traders.

"Bringing the army in to fight the drug war, as he now suggests, would also be disastrous. The fight against drugs has to be balanced so that it does not infringe on the rights and well-being of citizens," Gaviria said.

He also told Duterte that applying severe penalties and extrajudicial violence against drug users would only stop them from finding treatment and make them resort to criminal activities.

"A successful president makes decisions that strengthen the public good. This means investing in solutions that meet the basic standards of basic rights and minimize unnecessary pain and suffering. The fight against drugs is no exception. Strategies that target violent criminals and undermine money laundering are critical. So, too, are measures that decriminalize drug users, support alternative sentencing for low-level nonviolent offenders and provide a range of treatment options for drug abusers," Gaviria concluded.

"This is a test that many of my Colombian compatriots have failed. I hope Mr. Duterte does not fall into the same trap."

Gaviria was president of Colombia from 1990 to 1994 and is a founding member of the Global Commission on Drug Policy.

His fight against drug gangs employed tough policing similar to that of Duterte's narcotics crackdown that has seen more than 7,600 people killed, with 2,500 slain in police operations and many of the remaining deaths attributed to vigilantes and turf wars.

Rights group Amnesty International said in a report last week that police at the frontlines of the campaign had behaved like the criminal underworld they are supposed to be suppressing, taking payments for killings and delivering bodies to funeral homes.