The head of Iran's judiciary warned on Sunday that those behind a recent wave of anti-government protests could expect punishment "without the slightest leniency".
What began earlier this month as demonstrations against the high cost of living boiled over into a broader protest movement that represented the gravest challenge to the country's clerical leadership in years.
The protests have abated following a government crackdown, carried out under an internet blackout that left the country largely cut off from the outside world.
"The people rightly demand that the accused and the main instigators of the riots and the acts of terrorism and violence be tried as quickly as possible and punished if found guilty," judicial chief Gholamhossein Mohseni Ejei was quoted as saying by the official Mizan online news portal.
He went on to say "the greatest rigor must be applied in the investigations," but insisted that "justice entails judging and punishing without the slightest leniency the criminals who took up arms and killed people, or committed arson, destruction and massacres".
The Iranian government has put the death toll from the protests at 3,117, including 2,427 people it has labelled "martyrs" -- a term used to distinguish members of the security forces and innocent bystanders from those described by authorities as "rioters" incited by the US and Israel.
Rights groups, however, have said protesters account for the vast majority of the deaths, documenting several thousand killed, with the Norway-based NGO Iran Human Rights saying the final figure could top 25,000 dead.
- 'Just in case' -
The US-based Human Rights Activists News Agency (HRANA) has said more than 26,000 people have been arrested in relation to the demonstrations.
Iran is the world's second most prolific user of the death penalty after China, and the soaring number of arrests and vows of stiff punishment have raised fears it could use executions to repress dissent.
US President Donald Trump has threatened to intervene militarily should Iran begin putting protest suspects to death, but has recently softened his rhetoric after claiming Tehran had suspended planned executions.
On Thursday, he told reporters on the way back from Davos that the United States was nonetheless sending a "massive fleet" toward Iran "just in case".
The United States carried out strikes on Iranian nuclear facilities in June when it briefly joined Israel's 12-day war against the country.
Rights groups have accused authorities of repeatedly using live ammunition on protesters, but Colonel Mehdi Sharif Kazemi, commander of Iran's special police, maintained authorities had used only non-lethal measures such as water cannons to quell the unrest.
"The use of weapons (by the police) during this operation has sparked some criticism, but in fact, the police did not resort to using any firearms," he was quoted as saying by the Mehr news agency on Sunday.
"We used non-lethal means in order to guarantee the safety of the population and avoid any killings."
