PHNOM PENH : The former "first lady" of Cambodia's murderous Khmer Rouge regime died Saturday, according to a UN-backed tribunal, without victims ever seeing her face trial on charges of genocide and crimes against humanity.

Ieng Thirith, a French-educated revolutionary who was 83 when she died, was one of the few women in the leadership of the communist movement behind the horrors of the "Killing Fields" era. She was among just a handful of suspects charged by Cambodia's UN-backed war crimes court, but was freed in 2012 when the case against her was suspended after the court ruled she was unfit to stand trial due to progressive dementia.

Family ties helped her reach the upper echelons of power in a murderous totalitarian regime that tore children from parents and husbands from wives. The sister-in-law of late Khmer Rouge leader Pol Pot, she served as the regime's social affairs minister alongside her husband, former foreign minister Ieng Sary.

She had been hospitalised this year in Thailand with heart, bladder and lung problems. She passed away in a former Khmer Rouge stronghold on the Thai border where many regime leaders settled after they were ousted by the Vietnamese.

"The accused passed away at approximately 10.30 am (0330 GMT) on 22 August in Pailin, Cambodia," the UN-backed tribunal said in a statement. "She was released under a regime of judicial supervision. She remained under judicial supervision until her death," the statement from the Extraordinary Chambers in the Courts of Cambodia (ECCC) added. "Her body will be cremated on Monday evening," her son Ieng Vuth told AFP by telephone from Pailin, adding his mother had died from cardiac arrest.