Nuri al-Maliki, the Shia prime minister of Iraq, had said he wanted Saddam hanged this year for the killings, torture and other crimes against the Shia population of the town of Dujail in the 1980s.
But some of Saddam's fellow Sunnis have said that this can reinforce their alienation and many ethnic Kurds want Saddam first convicted of genocide against them.
The Iraqi High Tribunal confirmed in a Website posting that an appeal against Saddam's death sentence had failed. The judge who first announced the ruling on Tuesday had referred to a statute which says hangings must take place within 30 days of the failure of an appeal.
But two senior officials told Reuters on Thursday that the execution would only happen within 30 days if Iraq's president issued a decree ordering an immediate execution. That seems unlikely.
If he does not do so in that time the justice ministry can carry out the sentence any day it chooses.
The cabinet and president have declined requests for comment on the timing. Under the penal code, a religious holiday lasting until January 6 means no execution should take place before that.
Bosho Ibrahim, the deputy justice minister, from the Kurdish minority, said: "The justice ministry will not implement it before one full month is up.
"After one full month the justi
ce ministry can decide when it will carry out the execution."
"After one full month, the justice ministry can decide when it will carry out the execution"
Bosho Ibrahim, the deputy justice minister of Iraq
Jalal Talabani, the president and a Kurd, has refused to sign death warrants in other cases, but has delegated his powers to his Shia and Sunni vice-presidents. In any event, both the constitution and High Tribunal statutes deny the presidency the power to block executions ordered for such serious crimes.
Raed Jouhi, the tribunal spokesman said: "There are two options.
"In death sentences issued by our court, if there is a presidential decree within 30 days, then they can carry it out at any time. But if there is no decree, then after these 30 days it becomes obligatory in any case and it will be up to the justice ministry to decide when it wants to carry it out."
The United States has welcomed the court's ruling on Saddam and two of his aides who face similar sentences. However, there have been security concerns over the possibility of Sunni unrest if the executions go ahead.
Violence already is killing dozens of people a day and has forced hundreds of thousands of Iraqis to flee their homes, many for points abroad. In the past month, over 100,000 have registered for aid as internal refugees.
The US military reported five more military deaths on Thursday, taking the number to die since the March 2003 invasion to at least 2989. A car bomb near a Baghdad stadium killed 10 people and two other bombs killed a further seven in the city.