President Hassan Rouhani attended but did not speak at the main rally in Tehran, which coincided with seemingly deadlocked nuclear talks between Iran and world powers led by the United States.
In Iraq, thousands of people marched including hundreds of fighters in military uniform on Palestine Street in the capital Baghdad.
A demonstration in Lebanon was also expected to mark the annual solidarity day inaugurated by Iran’s revolutionary leader Ayatollah Ruhollah Khomeini.
While Iran does not recognise Israel’s existence, and supports Palestinian militant groups that fight it, Saudi Arabia’s bombing campaign in Yemen drew anger. The crowd in Tehran chanted “Down with US, Israel and the House of Saud,” and carried placards that declared “Zionist soldiers kill Muslims” and “the Saudi family will fall”.
While the ongoing nuclear negotiations in Vienna are at the forefront of Iranian minds, the talks were only a backdrop to the procession in the capital.
Iran’s relations with Saudi Arabia have sunk in the past six months since the Sunni kingdom began a bombing campaign against fellow Shia in Yemen.
Tehran also accuses Riyadh of backing Sunni extremists in Iraq and Syria, including ISIS.
