An Iraqi court is preparing to give its verdict on whether Saddam Hussein is guilty of crimes against humanity and if so, whether he should be executed.
The trial was to begin at 0700GMT, but it is believed the judges are still discussing the verdicts.
Stringent security measures have been imposed on Baghdad as Iraqis wait to learn their former leader's fate.
Fearing violence from his Sunni Arab supporters, the government imposed a curfew and cancelled all army leave.
Few Iraqis think the trial verdict will ease conflict, the BBC's Andrew North in Baghdad says.
Almost three years since Saddam Hussein was captured, soaring sectarian violence has brought Iraq to the brink of civil war.
Even those Iraqis who want to see their former leader dead do not believe his execution would make things any better, according to our correspondent.
Many critics have dismissed the trial as a form of victors' justice, given the close attention the US has paid to it.
Saddam Hussein faced trial on charges of crimes against humanity
Lawyers for Saddam Hussein have also accused the government of interfering in the proceedings - a complaint backed by US group, Human Rights Watch.
The former leader's lawyers have also attacked the timing of the planned verdict - days before the US votes in mid-term elections.
US President George W Bush's Republican Party is at risk of losing control of Congress in part because of voter dissatisfaction over its handling of the Iraq conflict.
The former Iraqi leader and seven co-defendants are accused of ordering the deaths of 148 Shias in 1982 in the village of Dujail, following an assassination attempt on Saddam Hussein.
The charge carries the death penalty, which is likely to be enforced by hanging - although Saddam Hussein has said in court that he would rather be executed by firing squad.
A second trial, for the former leader's crackdown on Iraq's Kurdish community, has yet to reach a conclusion.
Sunni Arab support
In a televised speech on Saturday, Nouri Maliki, Iraq's Shia Arab prime minister, said he hoped Saddam Hussein would get "what he deserves" for "crimes against the Iraqi people".
Nouri Maliki has called for calm ahead of the verdict
Our correspondent says Mr Maliki's statement provoked some surprise, given the continuing sectarian violence in Iraq.
Mr Maliki said Iraqis should mark the verdict in a way that "does not risk their lives".
A guilty verdict is widely expected against Saddam Hussein and his co-defendants, and the government fears his supporters among Iraq's Sunni Arab community will react violently.
Sunni Arabs have also supplied the backbone of Iraq's insurgency, launching attacks on Shia Muslims and US troops.
Sunday's security measures include a curfew in Baghdad, a city of six million people, that bans all vehicle and pedestrian traffic.
The city's civilian airport is also to remain closed.
Three nearby provinces, including Salahuddin, which contains Saddam Hussein's hometown of Tikrit, are also under curfew.
Correspondents say a violent reaction would not be surprising in Salahuddin, north of Baghdad, nor in Anbar to the west of the capital - where no curfew has been announced.
The BBC's Hugh Sykes in Baghdad says it is hard to enforce a curfew in Anbar as many of Saddam's former police, senior army officers and Baath Party officials lived in the two main towns there - Falluja and the provincial capital, Ramadi.
But elsewhere, especially in Kurdish and Shia areas, there may be celebrations if Saddam Hussein is found guilty.