Iran has executed 13 members of a Sunni rebel group blamed for a spate of attacks in the south-east of the country, Iran's state news agency says.
They were members of Jundallah (God's Soldiers). The execution of the brother of their leader was postponed, the agency reported.
Tehran blames the group for a series of attacks including the bombing of a mosque in May which killed 25 people.
Amnesty International had appealed for a stay of execution.
It said that the convicts had not received a fair trial.
Ebrahim Hamidi, who heads the judiciary in south-eastern Sistan-Baluchestan province, told the official Irna news agency on Tuesday that 13 of the group had been hanged inside a jail in the city of Zahedan.
"After last minute consultations, the executions were carried out in a prison," Mr Hamidi is quoted as saying.
Fars, a semi-official news agency, had earlier reported that the executions would be carried out in public.
Abdolhamid Rigi, the brother of the group's leader Abdolmalek Rigi, was not among those hanged on Tuesday but would be executed later this week, the report said.
'Executed in prison'
Iran state radio quoted Zahedan's prosecutor, Mohammad Marzieh, as saying that the men had been hanged for killing dozens of civilians, policemen and for bombings in the region.
Most people in Sistan-Baluchestan are Sunni Muslims and ethnic Baluchis.
The provincial capital Zahedan, near the border with Afghanistan and Pakistan, is the centre of a rebellion by Baluchis.
Predominantly Shia Muslim Iran says that Jundollah is part of the Sunni Islamist al-Qaeda network.
Jundallah has claimed repeated attacks in the province, including a bombing in May in a Shia mosque in Zahedan that killed 25 people, Iranian media say.
In recent weeks the Iranian government has increased the already high number of executions, possibly as a way of asserting its authority in the wake of the disputed presidential election result, says the BBC's Jon Leyne.
Human rights groups accuse Iran of making excessive use of the death penalty but Tehran insists it is an effective deterrent that is used only after a lengthy judicial process.