Nigeria's Senate on Thursday proposed significantly toughening penalties for drug trafficking, making the death penalty the new maximum sentence through a law amendment.

The amendment, which is not yet law, replaces life imprisonment, which was previously the harshest punishment.

Nigeria, Africa's most populous country of more than 200 million people, has in recent years gone from being a transit point for illegal drugs to a full-blown producer, consumer and distributor.

Opioid abuse, especially tramadol and cough syrups containing codeine, has been widespread throughout Nigeria, according to the National Agency for Food and Drug Administration and Control, which banned production and import of codeine cough syrup in 2018.

While cannabis is cultivated locally, cocaine, methamphetamine and other narcotics are trafficked through the country alongside opioids to feed a growing addiction problem.

The legislation stemmed from a report by the Senate committees on judiciary, human rights and legal matters, and drugs and narcotics, which Senator Mohammed Monguno presented during Thursday's plenary session.

Supporters argued the threat of execution would serve as a stronger deterrent to drug traffickers than life imprisonment.

Lawmakers who opposed the measure expressed concerns about the irreversible nature of the death penalty and the possibility of wrongful convictions.

The House of Representatives earlier passed the bill but without a death penalty provision. Five select members of the Senate and House will need to harmonize the two versions before it goes to the president.