Trump says Iran 'want to negotiate' after reports of hundreds killed in protests

US President Donald Trump said Sunday that Iran's leadership had called him seeking "to negotiate" after he repeatedly threatened to intervene militarily if Tehran killed protesters.

For two weeks, Iran has been rocked by a protest movement that has swelled in spite of a crackdown rights groups warn has become a "massacre".

Initially sparked by anger over the rising cost of living, the demonstrations have evolved into a serious challenge of the theocratic system in place since the 1979 revolution.

Information has continued to trickle out of Iran despite a days-long internet shutdown, with videos filtering out of capital Tehran and other cities over the past three nights showing large demonstrations.

As reports emerge of a growing protest death toll, and images show bodies piled outside a morgue, Trump said Tehran indicated its willingness to talk.

"The leaders of Iran called" yesterday, Trump told reporters aboard Air Force One, adding that "a meeting is being set up... They want to negotiate."

He added, however, that "we may have to act before a meeting".

The US-based Center for Human Rights in Iran (CHRI) said it had received "eyewitness accounts and credible reports indicating that hundreds of protesters have been killed across Iran during the current internet shutdown".

"A massacre is unfolding," it said.

The Norway-based NGO Iran Human Rights (IHR) said it confirmed the killing of at least 192 protesters but that the actual toll could be much higher.

"Unverified reports indicate that at least several hundreds, and according to some sources, more than 2,000 people may have been killed," said IHR.

More than 2,600 protesters have been arrested, IHR estimates.

A video circulating on Sunday showed dozens of bodies accumulating outside a morgue south of Tehran.

The footage, geolocated by AFP to Kahrizak, showed bodies wrapped in black bags, with what appeared to be grieving relatives searching for loved ones.

Near paralysis

In Tehran, an AFP journalist described a city in a state of near paralysis.

The price of meat has nearly doubled since the start of the protests, and many shops are closed. Those that do open must close at around 4:00 or 5:00 pm, when security forces deploy en masse.

There were fewer videos showing protests on social media Sunday, but it was not clear to what extent that was due to the internet shutdown.

One widely shared video showed protesters again gathering in the Pounak district of Tehran shouting slogans in favour of the ousted monarchy.

The protests have become one of the biggest challenges to the rule of supreme leader Ayatollah Ali Khamenei, 86, coming in the wake of Israel's 12-day war against the Islamic republic in June, which was backed by the United States.

State TV has aired images of burning buildings, including a mosque, as well as funeral processions for security personnel.

But after three days of mass actions, state outlets were at pains to present a picture of calm returning, broadcasting images of smooth-flowing traffic on Sunday. Tehran Governor Mohammad-Sadegh Motamedian insisted in televised comments that "the number of protests is decreasing".

The Iranian government on Sunday declared three days of national mourning for "martyrs" including members of the security forces killed.

President Masoud Pezeshkian also urged Iranians to join a "national resistance march" Monday to denounce the violence.

In response to Trump's repeated threats to intervene, Iran's parliament speaker Mohammad Bagher Ghalibaf said Iran would hit back, calling US military and shipping "legitimate targets" in comments broadcast by state TV.

'Stand with the people'

Reza Pahlavi, the US-based son of Iran's ousted shah, who has emerged as an anti-government figurehead, said he was prepared to return to the country and lead a democratic transition.

"I'm already planning on that," he told Fox News on Sunday.

He later urged Iran's security forces and government workers to join the demonstrators.

"Employees of state institutions, as well as members of the armed and security forces, have a choice: stand with the people and become allies of the nation, or choose complicity with the murderers of the people," he said in a social media post.

He also urged protesters to replace the flags outside of Iranian embassies.

"The time has come for them to be adorned with Iran's national flag," he said.

The ceremonial, pre-revolution flag has become an emblem of the global rallies that have mushroomed in support of Iran's demonstrators.

In London, protesters managed over the weekend to swap out the Iranian embassy flag, hoisting in its place the tri-colored banner used under the last shah.