Tehran, Iran: Chants against the Saudi royal family and the Islamic State group mingled with the traditional cries of "Death to Israel" and "Death to America" at Jerusalem Day rallies across Iran on Friday.

The annual show of solidarity with the Palestinians, during which hundreds of thousands of Iranians take to the streets, was launched by the Islamic republic's late revolutionary leader Ayatollah Ruhollah Khomeini and is now also marked by its allies across the Middle East.

This year's commemoration coincided with an intensifying battle for influence in the region between Shiite Iran and its Sunni arch rival Saudi Arabia, which severed diplomatic relations with Tehran in January 2016.

"Death to the House of Saud and Daesh (IS)," the demonstrators chanted. "Death to America", "Death to Israel", "Death to the UK".

Iran has been heavily involved in the war against IS in both Iraq and Syria, where it has trained and advised militias to fight the jihadists.

On Sunday, Iran fired six 750-kilometre (470-mile) range missiles at an IS base in eastern Syria, days after the jihadist group claimed twin bombing and shooting attacks in Tehran that left 17 people dead.

On Friday, Iran's Revolutionary Guards displayed some of the same Zolfaghar missiles used in the strike at Valiasr Square in the heart of the capital, alongside a 2,000-kilometre (1,250-mile) range Qadr missile.

Iran's ballistic missile programme has been the subject of persistent concern in Washington and the target of repeated US sanctions.

Some demonstrators burnt Israeli and American flags, while others carried a coffin plastered with a picture of US President Donald Trump and the slogan: "Death to America, death to the House of Saud."

In a speech to the crowd in the capital, parliament speaker Ali Larijani called Israel the "mother of terrorism".

"The displacement of millions of Muslims by the Zionist regime is unprecedented in the history of all terrorist groups," he said.

- Anti-Rouhani slogans -

President Hassan Rouhani, who joined the march through Tehran, hit out at a new sanctions bill approved by the US Senate, while videos on social media showed a small group of protesters chanting hostile slogans.

Reformist sites posted videos showing hardliners shouting "down with liar" and "down with the American cleric".

They warned that Rouhani could face the same fate as Abolhassan Bani-Sadr, Iran's first elected president after the 1979 Islamic revolution, who was impeached by parliament in 1981, less than two years later.

One video showed Rouhani's security guards rushing him into his car while others prevented protesters from approaching.

Last week, Iran's supreme leader Ayatollah Ali Khamenei had warned those who created "polarisation" could face the same fate as Bani-Sadr, without giving names.

The rare protest on Friday came one month after a mob attacked Rouhani's car when he visited a mine in northern Iran where 43 miners had been killed in an accident.

Other videos showed First Vice President Eshaq Jahangiri and outspoken MP Ali Motahari being heckled by angry protesters.

Rouhani's three female deputies were first to respond on Twitter.

"The ugly action of a small group insulting the president cannot damage national unity... and the strong support for Mr Rouhani," wrote Massoumeh Ebtekar, the president's deputy on environmental affairs.

"Insulting the president on Al-Quds (Jerusalem) Day is an unbefitting response by the extremists to the nation's choice," tweeted Zahra Ahmadipour, vice president for cultural heritage and tourism.

The interior ministry issued a statement saying an investigation into the "illegal" actions was under way.

Also for Jerusalem Day, Iranian authorities unveiled a large panel at Palestine Square in central Tehran, counting down "the days left until the destruction of Israel". 

The figure of 8,411 days -- or just over 23 years -- on the panel is based on a speech which Khamenei gave nearly two years ago predicting Israel would no longer exist by 2040.