Chants of "death to the dictators" have been heard in Iran and the country's state broadcasting building has gone up in flames.
Demonstrations continue to spread around the Middle Eastern country over the plunging value of the currency and soaring inflation.
At least 36 people have been killed and some 2,076 citizens arrested since the widespread civil unrest began last month, according to the Human Rights Activists News Agency.
Witnesses in the capital Tehran and major cities of Mashhad and Isfahan said protesters gathered again in the streets today, chanting slogans against the Islamic Republic's clerical rulers.
Iranian state media, however, said cities across the country were calm.
In videos seen by GB News, protesters could be heard chanting "death to the dictator" as they gathered in large numbers, in an in apparent reference to Supreme Leader Ali Khamenei.
Footage has meanwhile circulated on social media of a building, believed to be the Islamic Republic of Iran's broadcasting (IRIB) building, in flames.
The current protests, the biggest wave of dissent in three years, began in Tehran's Grand Bazaar, with shopkeepers condemning the rial currency's free fall.
Protests have spread across the country
|GETTY
Unrest has since spread nationwide amid deepening distress over economic privations arising from rocketing inflation driven by mismanagement and Western sanctions and curbs on political and social freedoms.
Reza Pahlavi, the exiled son of Iran's late Shah toppled in the 1979 Islamic Revolution, has urged protesters to continue with demonstations.
He wrote to X: "Great nation of Iran, the eyes of the world are upon you. Take to the streets and, as a united front, shout your demands.
"I warn the Islamic Republic, its leader, and the Islamic Revolutionary Guard Corps that the world and [President Donald Trump] are closely watching you. Suppression of the people will not go unanswered."
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Protesters have been pictured tearing down the Islamic Republic flag
|REUTERS
President Trump earlier this week pledged to "rescue" protesters in Iran if security forces fire at them.
He wrote to Truth Social: "If Iran shoots and violently kills peaceful protesters, which is their custom, the United States of America will come to their rescue.
"We are locked and loaded and ready to go. Thank you for your attention to this matter!"
The UK Foreign Office (FCDO) has issued an urgent travel warning for Iran amid the widespread protests.
The fresh warning, issued late on Wednesday night, advises against all travel to the Middle Eastern nation.
It reads: "FCDO advises against all travel to Iran. If you are a British national already in Iran, either resident or visitor, carefully consider your presence there and the risks you take by staying.
"British and British-Iranian dual nationals are at significant risk of arrest, questioning or detention.
"Having a British passport or connections to the UK can be reason enough for the Iranian authorities to detain you."
The urgent warning also cautioned that Britons who find themselves in trouble in Iran will receive "extremely limited" support from the Government.
It adds: "No face-to-face consular assistance will be possible in an emergency and the UK government will not be able to help you."