TEHRAN, Nov 3, 2024 (BSS/AFP) - Iranian demonstrators gathered on Sunday outside the former US embassy in Tehran to mark the anniversary of the 1979 hostage crisis that has for decades shaped relations between Washington and Tehran.

The hostage crisis began in November 1979 following the Islamic revolution led by Iran's late supreme leader Ayatollah Ruhollah Khomeini which ousted the Western-backed Shah Mohammed Reza Pahlavi.

Students loyal to Khomeini stormed the embassy building and held 52 staff hostage for 444 days while demanding that Washington hand over Iran's recently toppled shah, who was being treated in the United States for cancer.

Washington officially broke off relations with Tehran in 1980, midway through the crisis, and they have been frozen ever since.

"Death to Israel, Death to America!" chanted crowds of Iranians outside the building, which is currently a museum known as the "Den of Spies", and covered with striking anti-American murals.

Others burnt the Israeli and US flags.

Iranians have held the rallies annually since 1979.

Revolutionary Guards chief Hossein Salami criticised Israel and the United States, saying they "cannot survive by slaughtering and killing Muslims."

"We always warn them that if they don't change their behaviour, they will go towards collapse and destruction," he said during a speech at the Tehran rally.

Similar demonstrations were held in other Iranian cities including Shiraz, Abadan, and Bandar Abbas.

Regional tensions have soared since the outbreak of the Gaza war in October 2023, triggered by the Palestinian Hamas militant group's unprecedented attack on Israel.

Israel, an ally of the US and long-standing foe of Iran, has since engaged in a deadly conflict with Iran-backed groups including Hamas and Hezbollah in Lebanon.

On October 26, Israel conducted air strikes on military sites in Iran in response to Tehran's October 1 attack on Israel, itself retaliation for the killing of Iran-backed militant leaders and a Revolutionary Guards commander.

Israel has warned Iran against responding to its attack.

Iran's supreme leader Ayatollah Ali Khamenei vowed on Saturday a harsh response against Israel and the US to attacks on Iran and its allies.

"The enemies, both the USA and the Zionist regime, should know that they will definitely receive a tooth-breaking response to what they are doing against Iran, the Iranian nation and the resistance front," Khamenei said in a speech to students in Tehran.

Sunday's event took place days ahead of the US elections pitting Republican Donald Trump against Democrat Kamala Harris.