Unrest in Iran has killed more than 500 people, a rights group said on Sunday, as Tehran threatened to target US military bases if President Donald Trump carries out his renewed threats to intervene on behalf of protesters.

With the Islamic Republic's clerical establishment facing the biggest demonstrations since 2022, Trump has repeatedly threatened to get involved if force is used on protesters.

According to its latest figures - from activists inside and outside Iran - US-based rights group HRANA said it had verified the deaths of 490 protesters and 48 security personnel, with more than 10,600 people arrested in two weeks of unrest.

Iran has not given an official toll and Reuters was unable to independently verify the tallies.

Trump was to meet with senior advisers on Tuesday to discuss options for Iran, a US official told Reuters on Sunday. The Wall Street Journal had reported that options included military strikes, using secret cyber weapons, widening sanctions and providing online help to anti-government sources.

"The military is looking at it, and we're looking at some very strong options," Trump told reporters travelling on Air Force One on Sunday night.

Trump said he was in contact with Iranian opposition leaders. He also said, without elaborating, that Iran's leaders had called him on Saturday and want to negotiate, and that he might talk to them.

Iranian Parliament Speaker Mohammad Baqer Qalibaf warned Washington against "a miscalculation."

"Let us be clear: in the case of an attack on Iran, the occupied territories (Israel) as well as all US bases and ships will be our legitimate target," said Qalibaf, a former commander in Iran's elite Revolutionary Guards.

Authorities intensify crackdown

The protests began on December 28 in response to soaring prices, before turning against the clerical rulers who have governed since the 1979 Islamic Revolution.

Iranian authorities accused the US and Israel of fomenting trouble and called for a nationwide rally on Monday to condemn "terrorist actions led by the United States and Israel," state media reported.

The flow of information from Iran has been hampered by an internet blackout since Thursday. Trump said on Sunday he would talk to Elon Musk about restoring internet access in Iran through his Starlink satellite service.

Footage posted on social media on Saturday from Tehran showed large crowds marching at night, clapping and chanting. The crowd "has no end nor beginning," a man is heard saying.

Footage from the northeastern city of Mashhad showed smoke billowing into the night sky from fires in the street, masked protesters and a road strewn with debris, another video posted on Saturday showed. Explosions could be heard.

Reuters verified the locations.

State TV showed dozens of body bags on the ground at the Tehran coroner's office, saying the dead were victims of events caused by "armed terrorists", as well as footage of loved ones gathered outside the Kahrizak Forensic Medical Centre in Tehran waiting to identify bodies.

UN Secretary-General Antonio Guterres said he was shocked by reports of violence by the Iranian authorities and urged maximum restraint. "The rights to freedom of expression, association & peaceful assembly must be fully respected & protected," he said on X.

Authorities on Sunday declared three days of national mourning "in honour of martyrs killed in resistance against the United States and the Zionist regime," according to state media.

Three Israeli sources, who were present for Israeli security consultations over the weekend, said Israel was on a high-alert footing for the possibility of any US intervention.

Israel and Iran fought a 12-day war in June 2025, which the United States briefly joined by attacking nuclear installations. Iran retaliated by firing missiles at Israel and an American air base in Qatar.

'Rioters and terrorists'

While Iranian authorities have weathered previous protests, the latest have unfolded with Tehran still recovering from last year's war and with its regional position weakened by blows to allies such as Lebanon's Hezbollah since the October 7, 2023 Hamas-led attacks against Israel.

Iran's unrest comes as Trump flexes US muscles internationally, having ousted Venezuelan President Nicolas Maduro, and discussing acquiring Greenland by purchase or force.

Iranian President Masoud Pezeshkian said Israel and the US was masterminding destabilisation and that Iran's enemies had brought in "terrorists ... who set mosques on fire ... attack banks, and public properties".

"Families, I ask you: do not allow your young children to join rioters and terrorists who behead people and kill others," he said in a TV interview, adding that the government was ready to listen to the people and to resolve economic problems.

Iran summoned Britain’s ambassador on Sunday to the foreign ministry over “interventionist comments” attributed to the British foreign minister and a protester removing the Iranian flag from the London Embassy building and replacing it with a style of flag used prior to the 1979 Islamic Revolution.

Britain's foreign office did not immediately reply to a request for comment.

Alan Eyre, a former US diplomat and Iran expert, thought it unlikely the protests would topple the establishment.

"I think it more likely that it puts these protests down eventually, but emerges from the process far weaker," he told Reuters, noting that Iran's elite still appeared cohesive and there was no organised opposition.

Iranian state TV broadcast funeral processions in western cities such as Gachsaran and Yasuj for security personnel killed in protests.

State TV said 30 members of the security forces would be buried in the central city of Isfahan and that six more were killed by "rioters" in Kermanshah in the west.

US ready to help, says Trump

Trump, posting on social media on Saturday, said: "Iran is looking at FREEDOM, perhaps like never before. The USA stands ready to help!!!"

In a phone call on Saturday, Israeli Prime Minister Benjamin Netanyahu and US Secretary of State Marco Rubio discussed the possibility of US intervention in Iran, according to an Israeli source present for the conversation.

Some protesters in the United States took to the streets in support of the demonstrators in Iran. In the Los Angeles neighbourhood of Westwood, a rental truck drove into a crowd of a few hundred people who were holding a rally in support of the Iranian protesters, the KNBC news outlet reported on Sunday.

Los Angeles Police officer Sean Murray said that, based on video news accounts, the driver was escorted away by police. Murray said it was not clear how many people were injured, but that all of the injured were treated at the scene.

Reza Pahlavi, the exiled son of Iran's last shah and a prominent voice in the fragmented opposition, said Trump had observed Iranians' "indescribable bravery". "Do not abandon the streets," Pahlavi, who is based in the US, wrote on X.