TEHRAN - Iran's parliament passed a long-awaited amendment to its drug trafficking laws on Sunday, raising the thresholds that can trigger capital punishment and potentially saving the lives of many on death row. The bill must still be approved by the conservative-dominated Guardian Council but gained parliamentary approval after months of debate, according to parliament's website and the ISNA news agency. According to rights group Amnesty International, Iran was one of the top five executioners in the world in 2016, with most of its hangings related to illicit drugs.

The watchdog noted sharp drops in the number of executions in Iran -- down 42 percent to at least 567 that year. The new law raises the amounts that can trigger the death penalty from 30 grams to two kilos for the production and distribution of chemical substances such as heroin, cocaine and amphetamines.

For natural substances such as opium and marijuana, the levels have been raised from five to 50 kilos. The amendment will apply retroactively, thus commuting the sentences for many of the 5,300 inmates currently on death row for drug trafficking.

It restricts the death penalty to criminals who lead drug-trafficking gangs, exploit minors below 18 years old in doing so, carry or draw firearms while committing drug-related crimes, or have a related previous conviction of the death penalty or a jail sentence of more than 15 years or life in prison.

Under the new bill, the punishment for those already convicted and given the death penalty or life in prison, other than those meeting the new execution requirements, will be commuted to up to 30 years in jail and a cash fine.

Defending the bill in a parliamentary debate last week, Hassan Norouzi, the spokesman of parliament's judicial and legal committee, said the costs for Iran's war on drugs have almost doubled since 2010.

He said more than 6 million people were involved in drugs in the country, 5.2 million of them addicts and 1.8 million users. The amendment had faced opposition from police officials who believed that reducing or removing the death penalty would embolden criminals.

But many judges had welcomed the softened law -- and stayed execution sentences as they awaited the results of the parliamentary debate, Norouzi said.