MANILA • Philippine President Rodrigo Duterte's campaign to bring back the death penalty for drug-related crimes has cleared a major hurdle, with supporters backing it in congress but critics denouncing the planned killings as inhumane.

The death penalty Bill, along with a proposed measure to punish children as young as nine as adult criminals, are key planks of his controversial drug war that has already claimed more than 6,500 lives.

A majority of politicians in the lower house of congress passed a second reading of the Bill on Wednesday night, clearing one of the biggest obstacles in proponents' plans to make the death penalty legal by May.

A third and final reading still needs to be held next week, although with no more debates as both sides agree passage is a formality.

Then, the Philippine Senate, which is similarly dominated by Mr Duterte's allies, would pass a counterpart Bill.

"We have hurdled the most difficult part," congressman Reynaldo Umali, a sponsor of the Bill, told Agence France-Presse.

The Bill limits the death penalty to drug-related crimes.

Possessing 500g of marijuana or 10g of cocaine, Ecstasy or heroin, would be crimes punishable by execution, as would manufacturing and selling drugs.

People who commit serious crimes such as murder and rape while under the influence of drugs could also be executed.

However, committing those crimes without being under the influence of drugs would be punishable only with jail terms. The Bill allows for execution by hanging, firing squad or injection.

Many Filipinos support Mr Duterte and his drug war, arguing extreme measures must be taken to halt crime.

Opponents voiced anger that the Philippines would bring back the death penalty 11 years after it was revoked, highlighting a corrupt justice system that would lead to innocent people being executed.

After capital punishment, another priority Bill for Mr Duterte is a companion Bill lowering the age of criminal liability to as low as nine years old, from 15 currently.

AGENCE FRANCE-PRESSE