Pro-government rallies in several Iranian cities drew thousands of marchers on Wednesday, following six days of unrest that have left at least 21 people dead.
State television broadcast live pictures of rallies in Kermanshah, Ilam and Gorgan, where marchers waved Iranian flags and pictures of supreme leader Ayatollah Ali Khamenei.
The boldest challenge to Iran’s established order in almost a decade had continued into Tuesday night, with posts and video footage on social media showing riot police deployed in force in several cities.
Hours earlier, the ayatollah accused Iran’s foes of fomenting the unrest.
On Wednesday, marchers voiced their support for the ayatollah, chanting: “The blood in our veins is a gift to our leader” and “We will not leave our leader alone”.
The protests, which began over economic hardships, have taken on a rare political dimension, with a growing number of young people calling on the ayatollah to step down.
They are the biggest since unrest in 2009 that followed the disputed re-election of then-president Mahmoud Ahmadinejad.
At least 21 people have been killed during the unrest, including two members of the security forces.
More than 450 protesters have been arrested in the capital Tehran in recent days, and hundreds of others were detained around the country, according to officials. A judicial official said some could face the death penalty.
“The seditionist rioters should be executed,” marchers chanted on Wednesday, while posters they carried said hostile “hidden hands” guided from the United States, Israel and the United Kingdom should be cut off.
In at attempt to control the flow of information and calls for anti-government gatherings, Tehran authorities have restricted access to the Telegram messaging app and Instagram, owned by Facebook Inc.
High prices, alleged corruption and mismanagement are fuelling the anger.
President Hassan Rouhani championed a deal struck with world powers in 2015 to curb Iran’s nuclear programme in return for the lifting of most international sanctions.
However, he has failed to deliver on promises of prosperity in the OPEC oil producer where youth unemployment reached 28.8 per cent last year.
The nuclear deal is facing its biggest challenge since it was struck, with US president Donald Trump due to decide by mid-January whether to continue waiving US sanctions or reimpose them.
The ayatollah accused Iran’s enemies of causing the unrest, which began as protests about economic hardship and corruption but have grown into political rallies, some of which have criticised him by name.
“In recent days, enemies of Iran used different tools including cash, weapons, politics and intelligence apparatus to create troubles for the Islamic Republic,” he said, in his first reaction to the unrest.
He did not name the enemies but Ali Shamkhani, secretary of the supreme national security council, said the United States, Britain and Saudi Arabia were behind the riots.
“Saudis will receive Iran’s unexpected response and they know how serious it can be,” Mr Shamkhani was quoted by Tasnim news as saying in an interview with Beirut-based Al Mayadeen TV.
The ayatollah said on his website that he would address the nation about the events “when the time is right”.
The United States rejected the suggestion that the protests were the work of foreign powers.
“We all know that’s complete nonsense,” said Nikki Haley, the US ambassador to the United Nations.
“The demonstrations are completely spontaneous. They are virtually in every city in Iran. This is the precise picture of a long oppressed people rising up against their dictators.”
Washington will seek emergency sessions at the United Nations to express support for the protesters, Ms Haley said, adding that the international community had failed to support reformist protests in 2009 that were crushed by Tehran.