GENEVA, (Reuters) – U.N. human rights experts called on Iraq’s government on Tuesday not to carry out the death sentence passed on former leader Saddam Hussein, saying his trial had been seriously flawed.

The U.N. working group on arbitrary detention said the Iraqi tribunal had lacked independence and impartiality, had not given Saddam enough time to prepare his defence, and had restricted his access to his lawyers and right to call his own witnesses. “The working group also urges the Iraqi government to refrain from carrying out the sentence of death by hanging imposed in a proceeding, which does not meet applicable basic standards of a fair trial,” it said in a statement.

Iraq’s former dictator was condemned to death for crimes against humanity earlier this month for his role in the killings of 148 Shi’ite villagers after he escaped assassination in 1982. He is now standing trial for genocide against Iraqi Kurds in the late 1980s. Prosecutors have said the campaign included widespread use of chemical weapons, killed more than 180,000 people and destroyed hundreds of villages.

The U.N. group, composed of five independent legal and human rights experts, is headed by Algerian Leila Zerrougui. Its opinions have moral authority, but are not binding and the group lacks any enforcement powers.

The working group said it was reiterating concerns it expressed in September to the parties involved in which it said international standards had not been observed in Saddam’s trial.

It said the trial had violated provisions of the International Covenant on Civil and Political Rights — a binding international treaty and cornerstone of human rights law — to which both Iraq and the United States are parties. “The working group deems it necessary to issue this statement at this time, since it cannot be excluded that the death penalty imposed on Mr. Hussein would be carried out before the opinion is published in its annual report to the (U.N.)Human Rights Council,” it said.

It is not yet clear when Saddam might be hanged as defence lawyers can appeal. “What it recommends to the two governments is that the serious procedural shortcomings are redressed and that the situation of Mr. Hussein be brought in conformity with the principles of the Universal Declaration on Human Rights and with the provisions of the International Covenant on Civil and Political Rights,” the group said, without expanding.