Tens of thousands of Iranians took to the streets in mass rallies across the country to pledge allegiance to Supreme Leader Mojtaba Khamenei and demonstrate national unity.

The rallies, held concurrently in different cities on the birthday anniversary of the eighth Imam of Shiite Muslims Imam Reza, ran from 16:00 local time (1230 GMT) to 21:00 on Wednesday.

In the capital Tehran, people marched from Imam Hossein Square to Azadi Square, waving Iranian flags and holding pictures of the late Supreme Leader Ali Khamenei, who was killed in a US and Israeli attack in late February, and the new leader, reports Xinhua news agency.

Several officials, including Tehran Mayor Alireza Zakani and Iran's Constitutional Council spokesman Hadi Tahan Naizf, joined the crowd.

The participants chanted slogans against the United States and Israel and in support of Iran's Islamic establishment, and highlighted the necessity to maintain national unity.

A pavilion was set up along the route to commemorate those killed in a US and Israeli attack on a school in the southern Iranian city of Minab on the first day of the 40-day war against Iran.

Iran's homegrown "Kheibarshekan" missile and "Shahed 136" drone were also displayed during the rally in Tehran.

On February 28, Israel and the United States launched joint attacks on Tehran and other Iranian cities, killing Iran's then-Supreme Leader Ali Khamenei, senior commanders, and civilians. Iran responded with waves of missile and drone strikes targeting Israel and US assets in the Middle East. A ceasefire was achieved between the warring parties on April 8.