Saridewi Djamani, 45, was sentenced to death in 2018 for trafficking nearly 31 grams (1.09 ounces) of heroin, the Central Narcotics Bureau said.

It said the amount was "sufficient to feed the addiction of about 370 abusers for a week".

Human rights groups, international activists and the United Nations have urged Singapore to halt executions for drug offences, saying there is increasing evidence it is ineffective as a deterrent.

But its authorities insist capital punishment is important to halt drug demand and supply.

Singapore's laws mandate the death penalty for anyone convicted of trafficking more than 500 grams (17.64 ounces) of cannabis and 15 grams (0.53 ounces) of heroin.

It has executed 15 people for drug offences since it resumed hangings in March 2022, an average of one a month, human rights groups say.

Djamani's execution comes two days after a Singaporean man, Mohammed Aziz Hussain, 56, was executed for trafficking around 50 grams (1.75 ounces) of heroin.

The narcotics bureau said both prisoners were accorded due process, including appeals against their convictions and sentences, and petitions for presidential clemency.

Anti-death penalty campaigners said the last woman known to have been hanged in Singapore was Yen May Woen, a 36-year-old hairdresser, also for drug trafficking, in 2004.

Read more:
Man executed in Singapore over plot to smuggle one kilogram of cannabis
Singapore executes man with learning difficulties over drugs offence

Delivery driver to be executed

Transform Justice Collective, a Singaporean group advocating for the abolishment of capital punishment, said a new execution notice had been issued to another prisoner for 3 August - the fifth this year.

It said the prisoner is an ethnic Malay citizen who worked as a delivery driver before his arrest in 2016.

He was convicted in 2019 for trafficking around 50 grams (1.75 ounces) of heroin, it said.

The group said the man maintained in his trial he believed he was delivering contraband cigarettes for a friend he owed money. He did not verify the contents of the bag as he trusted his friend.

Although the court found he was merely a courier, the man still had to be given the mandatory death penalty, it said.

The group "condemns, in the strongest terms, the state's bloodthirsty streak" and reiterated calls for an immediate moratorium on the use of the death penalty.

Law punishes low-level traffickers and couriers, critics say

Critics say Singapore's harsh law merely punishes low-level traffickers and couriers and the nation is out of step with the trend of countries moving away from capital punishment.

Neighbouring Thailand has legalised cannabis while Malaysia ended the mandatory death penalty for serious crimes this year.