Iranian officials intensified a crackdown on protests across the country on Friday, threatening participants with the death penalty amid expectations of further unrest.

Supreme leader Ayatollah Ali Khamenei said the Islamic Republic would not tolerate “vandalism” or “people acting as mercenaries for foreign powers,” state-run Press TV reported.

A Tehran prosecutor later warned rioters who damage public property would face the death penalty.

The Islamic Revolutionary Guard Corps, charged with defending the pillars of the 1979 revolution, also issued a statement, saying “the continuation of this situation is unacceptable” and that it had the right to avenge “terrorist incidents”.

The comments indicate that authorities intend to increase the severity of their response to almost two weeks of demonstrations, despite President Masoud Pezeshkian describing protesters’ economic grievances as legitimate and ordering security forces to show restraint.

The protests have escalated into the most serious challenge to 86-year-old Khamenei and his theocratic government since a nationwide uprising in 2022.

Iranian state television images showing cars driving past burning vehicles in Tehran. Photograph: Iranian state TV via APIranian state television images showing cars driving past burning vehicles in Tehran. Photograph: Iranian state TV via AP

They started in Tehran’s Grand Bazaar on December 28th after a slump in the value of Iran’s currency to record lows, worsening a cost-of-living crisis in the sanctions-hit economy.

The death toll since the unrest began has risen to 42, according to the US-based Human Rights News Agency, which tracks protests and the activities of political activists in Iran. The BBC said it had independently confirmed at least 21 of the fatalities.

The Opec member’s situation has been worsened by corruption and by oil prices falling heavily in the past year.

The unrest disrupted air travel in and out of the country. Non-Iranian airlines cancelled all Friday flights between Tehran and Istanbul, with additional delays and cancellations in Dubai, according to airport websites.

Monitoring group Netblocks on Thursday reported a nationwide shutdown of the internet in Iran. Various efforts to reach individuals in the country by landline and mobile phone failed.

One Tehran resident said phone calls were not working at all or were cutting in and out, and text messages were heavily restricted.

Iranian authorities frequently resort to such tactics during periods of unrest as they seek to prevent people sharing images of state violence against civilians.

Even so, videos posted on X and Instagram overnight showed large numbers of people gathered on several major streets in different areas of Tehran, the capital. One clip appeared to show hundreds in a central thoroughfare in the Karim Khan neighbourhood chanting “death to the dictator”.

In the city of Isfahan, protesters pulled down the entrance sign of a branch of state TV – which has downplayed the protests – while flames burned in the background.

In at least one post, the chant of “Long live the shah” can be heard. That is a reference to the late Shah of Iran – deposed during the 1979 revolution – and his son, Reza Pahlavi, who lives in exile in the United States.

Mr Pahlavi (65) says he wants to lead a transition to democracy in Iran and has urged Iranians to protest. On X, he called on them to “make the crowd even larger” on Friday evening.

US president Donald Trump on Thursday called Mr Pahlavi a “nice person” but said he wasn’t sure that it would be “appropriate” to meet him. The rule of Mr Pahlavi’s father was widely despised and its overthrow gave birth to the Islamic Republic.

“I think that we should let everybody go out there, and we’ll see who emerges,” Mr Trump said in an interview. He reiterated warnings to Iran against killing protesters, saying: “If they do that, they’re going to have to pay hell.”

Mr Khamenei said Mr Trump should “focus on running own country if capable” and that his hands are “stained with blood” after the US and Israeli air strikes on Iran in June. – Bloomberg