On Wednesday, Singapore executed a man accused of coordinating a cannabis delivery, despite pleas for clemency from his family and protests from activists.
The United Nations Human Rights Office had asked Singapore on Tuesday to "urgently reconsider" his scheduled execution over one kilogram of cannabis.
Activist Kirsten Han from the Transformative Justice Collective confirmed that the execution had been carried out, and that his family had been given the death certificate.
Tangaraju Suppiah, 46, was convicted in 2017 of "abetting by engaging in a conspiracy to traffic" 1,017.9 grams of cannabis, twice the minimum volume that merits the death sentence.
He was sentenced to death in 2018 and the Court of Appeal upheld the decision.
Why is the UN concerned?
Singapore has some of the world's toughest anti-drug laws and insists the death penalty remains an effective deterrent against trafficking.
However, the UN's Office of the High Commissioner for Human Rights disagrees. "The death penalty is still being used in a small number of countries, largely because of the myth that it deters crime," the office said in a statement.
"We have concerns around due process and respect for fair trial guarantees. The UN Human Rights Office calls on the authorities not to proceed with his execution," it added.
At a UN Human Rights briefing Tuesday, spokesperson Ravina Shamdasani called on the Singapore government to adopt a "formal moratorium" on executions for drug-related offenses.
"Imposing the death penalty for drug offences is incompatible with international norms and standards," she said.
Singapore slams Branson over execution criticism
Earlier, British billionaire Richard Branson, a member of the Geneva-based Global Commission on Drug Policy, had also urged Singapore to halt Tangaraju's execution.
Branson wrote on his blog on Monday that Tangaraju was "not anywhere near" the drugs at the time of his arrest and that Singapore may be about to put an innocent man to death.
In response, Singapore's Home Affairs Ministry said in on Tuesday that Tangaraju's guilt had been proven beyond a reasonable doubt.
Branson showed "disrespect for Singapore's judges and our criminal justice system with such allegations", it added.
Rights groups call for abolishment of death penalty
Cannabis has been decriminalized in many parts of the world, including in neighbouring Thailand, and rights groups have been calling for Singapore to abolish capital punishment.
Many of Singapore's neighbours have no death penalty or have observed moratoria on executions, including Malaysia, which earlier this month passed sweeping legal reforms to end mandatory capital punishment.
Tangaraju's family have sent letters to Singapore's president seeking clemency and retrial, while the local missions of the European Union and its member states have jointly called for him to be given a non-capital sentence.
Singapore resumed executions in March 2022 after a hiatus of more than two years. If Tangaraju is hanged, it would be the country's first execution in six months. Eleven executions were carried out last year, all for drug offenses.