New York [US], January 3 (ANI): Iran's permanent representative to the United Nations, Amir Saeed Iravani, has written to the UN secretary-general and the president of the UN Security Council, urging international condemnation of what he described as 'unlawful threats' directed at Tehran by United States President Donald Trump, amid continuing protests across Iran.

The letter was dispatched on Friday, hours after Trump warned that the US was 'locked and loaded and ready to go' if further protesters were killed during demonstrations triggered by rising living costs.

In the letter, Iravani called on UN chief Antonio Guterres and Security Council members to 'unequivocally and firmly condemn' Trump's 'reckless and provocative statements', saying they constituted a 'serious violation' of the UN Charter and international law.

'Any attempt to incite, encourage or legitimise internal unrest as a pretext for external pressure or military intervention is a gross violation of the sovereignty, political independence and territorial integrity of the Islamic Republic of Iran,' Iravani wrote in the letter, which was published in full by Iran's state-run IRNA news agency.

The communication further stated that Iran's government 'reiterates its inherent right to defend its sovereignty' and would 'exercise its rights in a decisive and proportionate manner'.

'The United States of America bears full responsibility for any consequences arising from these illegal threats and any subsequent escalation of tensions,' Iravani added.

According to IRNA, protests continued on Friday in multiple Iranian cities, including Qom, Marvdasht, Yasuj, Mashhad and Hamedan.

Demonstrations were also reported in Tehran neighbourhoods such as Tehranpars and Khak Sefid.

The unrest spread nationwide after shopkeepers in Tehran went on strike on Sunday over soaring prices and prolonged economic stagnation.

Officials said at least nine people have been killed and 44 arrested so far.

The deputy governor of Qom province said another individual died after a grenade exploded in his hand, describing the incident as an attempt to provoke unrest.

In a post on Truth Social, Trump said that if Iran 'violently kills peaceful protesters, which is their custom, the United States of America will come to their rescue'.

Ali Larijani, secretary of Iran's Supreme National Security Council, responded by saying US interference 'is equivalent to chaos across the entire region and the destruction of American interests'.

Iran continues to face deep economic challenges, including a rapidly depreciating currency and high inflation.

These pressures have been compounded by years of severe drought in Tehran, a city of around 10 million people.

Iranian leaders have struck a relatively conciliatory tone, with President Masoud Pezeshkian saying the government is at 'fault' for the situation and pledging to seek solutions.

Tensions between Tehran and Washington remain high following US strikes on three Iranian nuclear sites in June during a 12-day escalation involving Israel.

Trump later described the operation as a 'very successful attack'.

Last week, during a joint appearance with Israeli Prime Minister Benjamin Netanyahu, Trump warned that the US would 'knock the hell out' of Iran if it advanced its nuclear or ballistic weapons programmes.

The remarks came amid renewed Israeli efforts to resume attacks on Iran.

Pezeshkian has said Iran would respond with a 'severe' reaction to any aggression. (ANI)