IRANIAN security forces have fired live rounds and tear gas at thousands of protesters in the capital, it is reported.

Thousands of anti-government demonstrators took to the streets in Tehran last night to demand the resignation of the country's supreme leader.

12 Gunman seen holding a shotgun on the streets of Tehran

12 Riot police clashed with protesters as they chanted for the leader's resignation Credit: Twitter

12 Huge crowds gathered as they chanted against the Iranian leader Credit: Getty - Contributor

12 Crowds of people flee after gunshots rang out in Tehran Credit: AP:Associated Press

12 People flee in terror amid fears of a bloody crackdown on protests Credit: AP:Associated Press

12 Shocking footage captured a trail of blood leading to crowds on the streets of Tehran

The demonstrations were sparked by the country's admission that it shot down a passenger plane near Tehran killing 176 people - including 82 Iranians - after denying it for days.

Footage shows crowds chanting anti-government slogans and tearing down posters of Qasem Soleimani, the top general whose killing by a US drone sparked a chain of events that led to the plane tragedy.

But there are fears the protests are being met with a bloody crackdown - just like similar demonstrations last year that saw 1,500 people killed.

Videos posted on Twitter show crowds of civilians screaming in terror and running down streets with gunfire heard in the background.

'OH MY GOD, SHE'S BLEEDING'

One clip shows a woman with blood pouring from what appears to be gunshot wound.

Those around her cry out that she has been shot in the leg, with one screaming: "Oh my God, she's bleeding non-stop!"

Another shouts: "Bandage it!"

Other images show a militia man holding a shotgun running away from the scene.

One local journalist tweeted: "The Iranian Revolutionary Guards are firing live ammunition against the protesters in... Tehran."

Another said: "Gunshots and tear gas fired at Iranian protesters. The Islamic Republic has resorted to violence.

"The lives of the Iranian people are in danger."

While another added: "The Iranian people say: We do not want the Islamic Republic. Be the voice of the Iranian people."

Another video shows Iranians tearing down #Soleimani poster. You know why?

78 people killed in an stampede in his funeral, 178 people killed in exacting his revenge by downing #UkrainianPlane & 1500 killed by IRGC in #IranProtests . People are furious when you call him a hero. pic.twitter.com/2COgVHpsNV — Masih Alinejad 🏳️ (@AlinejadMasih) January 12, 2020

12 An explosion goes off sparking a stampede

12 Protesters gathered in Tehran furious after the Iranian regime admitted shooting down the plane Credit: Getty - Contributor

12 Tear gas was used on the angry crowds as they gathered in Tehran Credit: Twitter

12 Hundreds of people gathered after Iran admitted shooting down the Ukrainian plane Credit: Twitter

12 Fire and smoke could be seen as cops clashed with the crowds Credit: Twitter

Donald Trump, who has expressed support for past waves of anti-government demonstrations in Iran, addressed the country’s leaders in a tweet.

He wrote: “DO NOT KILL YOUR PROTESTERS. Thousands have already been killed or imprisoned by you, and the World is watching.

“More importantly, the USA is watching.

“Turn your internet back on and let reporters roam free! Stop the killing of your great Iranian people!”

It comes after UK diplomat Rob Macaire, 53, was detained after photographing demonstrators over the weekend.

Iranian students booed those who did step on the American/Israeli flags, at last there might be peace between our countries, we're all united to defeat the Islamic republic of Iran who oppress, torture & kill their own citizens. #MakeIranGreatAgain pic.twitter.com/zK54I6jNVt — Mark Kennedy 🇺🇸 (@RealMarkKennedy) January 12, 2020

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Foreign Secretary Dominic Raab said the arrest of the ambassador - who was appointed as envoy in March 2018 - is a "flagrant violation of international law".

He added: "The Iranian government is at a cross-roads moment.

"It can continue its march towards pariah status with all the political and economic isolation that entails, or take steps to deescalate tensions and engage in a diplomatic path forwards."

Soleimani was killed by a US airstrike last week Credit: AP:Associated Press

12 Soleimani's body has been paraded through a number of major cities in Iran Credit: AP:Associated Press