Tehran   -   Tens of thousands of Iranians gathered Tuesday to mourn president Ebrahim Raisi and seven members of his entourage who were killed in a helicopter crash on a fog-shrouded mountainside.

Waving Iranian flags and portraits of the late president, mourners set off from a central square in the northwestern city of Tabriz, where Raisi was headed when his helicopter crashed on Sunday.

They walked behind a lorry carrying the coffins of Raisi and those who died with him, who also included foreign minister Hossein Amir-Abdollahian. “We, the members of the government, who had the honour to serve this beloved president, the hardworking president, pledge to our dear people and leader to follow the path of these martyrs,” Interior Minister Ahmad Vahidi said in a speech.    The helicopter lost communications while it was on its way back to Tabriz after Raisi attended the inauguration of a joint dam project on the Aras river, which forms part of the border with Azerbaijan, in a ceremony with his counterpart Ilham Aliyev. A massive search and rescue operation was launched on Sunday when two other helicopters flying alongside Raisi’s lost contact with his aircraft in bad weather.

State television announced his death in a report early on Monday, saying “the servant of the Iranian nation, Ayatollah Ebrahim Raisi, has achieved the highest level of martyrdom”, showing pictures of him as a voice recited the Koran.       Killed alongside the president and the foreign minister were provincial officials and members of his security team.        Iran’s armed forces chief of staff Mohammad Bagheri ordered an investigation into the cause of the crash as Iranians in cities nationwide gathered to mourn Raisi and his entourage.

Tens of thousands gathered in the capital’s Valiasr Square on Monday.

On Tuesday, the Assembly of Experts, a key clerical body in charge of selecting or dismissing Iran’s supreme leader, held its opening session after its March election, with the seat reserved for Raisi carrying his portrait.

Raisi, who was widely expected to succeed current supreme leader Ayatollah Ali Khamenei, had been a member of the body since 2006.

Khamenei, who wields ultimate authority in Iran, declared five days of national mourning and assigned vice president Mohammad Mokhber, 68, as caretaker president until a presidential election can be held.

State media later announced that the election will be held on June 28.

Iran’s top nuclear negotiator Ali Bagheri, who served as deputy to Amir-Abdollahian, was named acting foreign minister.     From Tabriz, Raisi’s body will be flown to the Shiite clerical centre of Qom later Tuesday before being moved to Tehran during the evening.

Processions will be held in the capital on Wednesday morning before Khamenei leads prayers at a farewell ceremony.  Raisi’s body will then be flown to his home city of Mashhad, in the northeast, where he will be buried on Thursday evening after funeral rites.

Raisi, 63, had been president since 2021. The ultra-conservative’s time in office saw mass protests, a deepening economic crisis and unprecedented armed exchanges with arch-enemy Israel.

Raisi succeeded the moderate Hassan Rouhani, at a time when the economy was battered by US sanctions imposed over Iran. Condolence messages flooded in from Iran’s allies around the region, including the Syrian government, Palestinian group and Lebanese group.

Israel’s killing of seven Revolutionary Guards in a drone strike on the Iranian consulate in Damascus on April 1 triggered Iran’s first ever direct attack on Israel, involving hundreds of missiles and drones.

In a speech hours before his death, Raisi underlined Iran’s support for the Palestinians, a centrepiece of its foreign policy since the 1979 Islamic revolution.

Palestinian flags were raised alongside Iranian flags at ceremonies held for the late president.

The body of Iranian President Ebrahim Raisi has arrived in Tehran as part of funeral ceremonies scheduled to run over several days, according to state-run news agency IRNA.

A video broadcast by state media shows the presidential plane arriving at Tehran’s Mehrabad airport, carrying Raisi’s coffin. Government and military officials lined a red carpet, and many could be seen publicly weeping as a military escort carried the coffin.

According to images published by state media, a seat on the presidential plane was left empty, covered only in black cloth and a picture of Raisi laid upon it.

The funeral procession will continue to the holy Shiite city of Qom on Tuesday afternoon, where prayers are scheduled at the Fatima Masumeh shrine.

Earlier on Tuesday, funeral ceremonies began in the northwestern city of Tabriz, where large crowds dressed in black were seen lining Martyr’s Square and surrounding streets in the rain.

A large truck, adorned with flowers and draped in the Iranian flag, carried the coffins of Raisi, Foreign Minister Hossein Amir-Abdollahian and the others killed in Sunday’s helicopter crash through the crowds, the state media images show.

In a speech in Tabriz on Tuesday, Iranian Interior Minister Ahmad Vahidi said that Raisi and Amir-Abdollahian “set a model for brave service and diplomacy,” pointing to the Israel-Hamas war in Gaza.

“Who can forget Raisi’s heartfelt speeches in defense of Gaza?” Vahidi said, IRNA reported.

After the ceremonies in Qom, the bodies of Raisi and the others killed will be transported back to Tehran for more planned funeral ceremonies on Wednesday.