MANILA — A proposed law making its way through the Philippine Congress would consider children as young as 9 criminally responsible for their actions, drawing fierce opposition from rights advocates and opponents of President Rodrigo Duterte’s deadly antidrug campaign.

The justice panel in the House of Representatives hurriedly approved amendments on Monday to the country’s juvenile justice law, which was signed in 2006 and set the minimum age for criminal liability at 15. Mr. Duterte has repeatedly criticized the current law as tying the hands of law enforcement against underage offenders working for drug gangs. The measure still awaits approval by the full House.

Rights groups say Mr. Duterte’s antidrug campaign has been a human rights disaster for the Philippines, with thousands of drug dealers, users and others killed since he came to power in 2016.

Romeo Dongeto, head of the Philippine advocacy group Child Rights Network, said advocates around the world were “shocked and disappointed” by the proposed law, which he called a “stark mockery of the field of child development.”