Iranian state TV has said security forces killed what it called "thugs and rioters" during last month's mass protests against a petrol price rise.
Amnesty International has said at least 208 people were killed, but others have put the death toll at close to 400.
A judiciary spokesman has dismissed such reports as "utter lies".
The authorities have not yet released any overall casualty figures.
The protests erupted in cities and towns across Iran on 15 November, after the government announced that the price of petrol would rise by 50% to 15,000 rials a litre ($0.12; £0.09 at the unofficial market exchange rate), and that drivers would be allowed to purchase only 60 litres each month before the price rose to 30,000 rials.
The decision was met with widespread anger in a country where the economy is already reeling as a result of US sanctions that were reinstated last year when President Donald Trump abandoned a nuclear deal with Iran.
The authorities' decision to almost completely shut down access to the internet made it hard to gather information about what was happening on the streets, but the video footage that reached the outside world appeared to show security forces shooting at unarmed demonstrators.
Interior Minister Abdolreza Rahmani Fazli said last week that as many as 200,000 people took part in the protests, and 731 banks, 70 petrol stations and 140 government sites were set ablaze. More than 50 security bases were also attacked, he added.
On Monday night, Iran's state-run IRTV2 channel broadcast a report confirming that there were fatalities during the unrest, but did not give any figures. It categorised those killed as "armed thugs and rioters", security personnel, passers-by hit by crossfire or victims of "suspicious shootings".