SINGAPORE, Singapore -- Singapore on Friday hanged a 45-year-old citizen for drug trafficking, the city-state's first execution of a woman in nearly 20 years, officials said. The execution was carried out despite appeals from rights groups, who argue capital punishment has no proven deterrent effect on crime. "The capital sentence of death imposed on Saridewi Binte Djamani was carried out on 28 July 2023," the Central Narcotics Bureau said in a statement. She was convicted of trafficking "not less than 30.72 grams" of heroin, more than twice the volume that merits the death penalty in Singapore. Djamani, who was sentenced in 2018, "was accorded full due process under the law, and was represented by legal counsel throughout the process," the bureau said. "She appealed against her conviction and sentence, and the Court of Appeal dismissed her appeal on 6 October 2022," the bureau said, adding that her plea for presidential clemency was also rejected. Djamani is the first woman to be executed in the city-state since 2004, when Yen May Woen, a Singaporean, was hanged for drug trafficking, the bureau said. She became the 15th prisoner sent to the gallows since the government resumed executions in March 2022 after a two-year pause during the Covid-19 pandemic. A local man, Mohd Aziz bin Hussain, 57, was hanged on Wednesday for trafficking about 50 grams of heroin. A rights group said Friday it had confirmed that another drug convict on death row has been scheduled for execution on August 3. Singapore has some of the world's toughest anti-drug laws -- trafficking more than 500 grams of cannabis or over 15 grams of heroin can result in the death penalty. Rights groups, including Amnesty International, had urged the government to halt the executions this week, saying there was no evidence the death penalty acted as a deterrent to crime. "This is the fourth execution this year and there will be another one next week. It's horrible for the families and worrying for other death row inmates," Singaporean rights activist Kirsten Han told AFP. There "is no sign of the government wanting to give an inch," she added. "The number of women on death row in Singapore is relatively uncommon and there is no clear reason why there are fewer women." Billionaire Richard Branson on Thursday urged Singapore to "grant mercy" to Djamani and stop her execution. Singapore is among four countries –- along with China, Iran and Saudi Arabia –- confirmed to have executed prisoners for drug-related offenses last year, Amnesty said. Singapore insists the death penalty has helped make it one of Asia's safest countries.