The protests erupted across the sanctions-hit country on November 15, hours after the price of petrol was raised by as much as 200 percent.

Motorists blocked highways in Tehran before the unrest spread to cities and towns across the country, with petrol pumps torched, police stations attacked and shops looted.

"Incidents, big and small, caused by the rise in petrol price took place in (a little) less than 100 cities across Iran," said a statement on the Guards' official website.

The Guards said the "incidents were ended in less than 24 hours and in some cities in 72 hours" as a result of the "armed forces' insight and timely action".

The "arrest of the rioters' leaders has contributed significantly to calming the situation".

Protest leaders were arrested by the Guards' intelligence arm in the province of Tehran and Alborz as well as in the southern city of Shiraz, according to the statement.

A near-total internet blackout remained in effect on Thursday, with Iranians abroad tweeting hashtags like #Internet4Iran and calling for an end to the outage, now in its fifth day.

The United Nations human rights office has said it was alarmed by reports live ammunition had caused a "significant number of deaths".

Officials have confirmed five deaths, including of three security personnel stabbed by "rioters".

London-based rights group Amnesty International said more than 100 demonstrators were believed to have been killed and that the real toll could be as high as 200.

The full extent of the bloodshed was difficult to ascertain given the internet restrictions.

Iran's mission to the UN disputed the Amnesty toll in a tweet, saying figures "not confirmed by the government are speculative" and in many cases a "disinformation campaign waged against Iran".