Then-president Hamid Karzai called for the men to be hanged even before their trial was held last month, and he signed their death sentences shortly before leaving office a week ago.
The armed gang members, wearing police uniforms, stopped a convoy of cars returning to Kabul at night from a wedding in Paghman, a scenic spot near the capital popular with day-trippers.
The attackers tied up men in the group before raping at least four of the women and stealing valuables from their victims.
"The court's verdict on the execution of five men guilty in the Paghman robbery and rape case will be implemented tomorrow," Atta Mohammad Noori, chief of staff at the attorney general's office, told AFP today.
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"It is set to happen, unless there is a last-minute change in the decision."
The crime in the early hours of August 23 has become a symbol of the violence that women face in Afghanistan, despite reforms since the Taliban era.
"The proceedings... Risk denying adequate justice to both the victims of this terrible crime and the accused," the UN agency said in a statement.
Amnesty said the trials had been hurried, giving lawyers little time to prepare the defence. It was only nine days between the arrests and the handing down of death sentences by the primary court.
"(The trials) have been marred by inconsistencies, un-investigated torture claims and political interference," Amnesty said.