Singapore on Friday hanged a 55-year-old man for drug trafficking, its narcotics enforcement agency said, the city-state's third execution in a week as the United Nations called for a halt.

The UN and rights groups say capital punishment has no proven deterrent effect and have called for it to be abolished, but Singaporean officials insist it has helped make the country one of Asia's safest.

Singapore's Central Narcotics Bureau (CNB) said the death sentence was carried out for Rosman Abdullah, convicted of trafficking 57.43 grams (2.03 ounces) of heroin.

Under the country's tough drug laws, the death penalty kicks in for any amount above a 15-gram threshold.

The hanging at Changi prison followed the November 15 execution of two men -- a 39-year-old Malaysian and a 53-year-old Singaporean -- also for drug trafficking.

"Rosman was accorded full due process under the law, and was represented by legal counsel throughout the process," CNB said in a statement.

The Singaporean, first sentenced in July 2010, had exhausted his appeals, including one for clemency from the president.

His execution was the eighth this year in the city-state, seven for drug trafficking and one for murder.

According to an AFP tally, Singapore has hanged 24 people since it resumed carrying out the death penalty in March 2022 after a two-year halt during the Covid-19 pandemic.

The UN on Thursday reiterated its call on Singapore to review its position on capital punishment.

"The use of the death penalty for drug-related offences is incompatible with international human rights law. There is increasing evidence showing the ineffectiveness of capital punishment as a deterrent," UN Human Rights spokesperson Ravina Shamdasani said in a statement.

The CNB, however, said capital punishment was "imposed only for the most serious crimes, such as the trafficking of significant quantities of drugs which cause very serious harm" to users and society at large.

AFP

People attend a protest against the death penalty in Singapore in 2022. Photo: AFP

Singapore hangs third drug trafficker in a week