Foreign Minister Hossein Amir-Abdollahian was also among those killed, along with seven others.
His death comes at a fraught moment in the Middle East, with war raging in Gaza.
The helicopter crashed weeks after Iran launched a drone-and-missile attack on Israel in response to a deadly strike on its diplomatic compound in Damascus.
Hardliner Raisi became president in a historically uncompetitive election in 2021. Previously the chief justice, he oversaw a period of intensified repression of dissent in a nation convulsed by youth-led protests against clerical rule.
Raisi was the second-most powerful person in the Islamic Republic’s political structure after Supreme Leader Ayatollah Ali Khomeini. The Iranian Constitution mandates that, in the case of the president’s death, the first vice president assumes office with the approval of the Supreme Leader.
Iran was thrown into uncertainty Sunday as search and rescue teams scoured a fog-shrouded mountain area after President Ebrahim Raisi’s helicopter went missing in what state media described as an “accident”.
Fears grew for the 63-year-old ultraconservative after contact was lost with the aircraft carrying him as well as Foreign Minister Hossein Amir-Abdollahian and others in East Azerbaijan province, reports said.
The supreme leader, Ayatollah Ali Khamenei, urged Iranians to “not worry” about the leadership of the Islamic republic, saying “there will be no disruption in the country’s work”.
“We hope that Almighty God will bring our dear president and his companions back in full health into the arms of the nation,” he said in a nationally televised address as Muslim faithful prayed for Raisi’s safe return.
Expressions of concern and offers to help came from abroad, including Iraq, Kuwait, Qatar, Saudi Arabia, Syria, Russia, and Turkey, as well as from the European Union which activated its rapid response mapping service to aid in the search effort.
Iran’s foreign ministry spokesman Nasser Kanani expressed gratitude for “governments and international organizations for their sympathy and offer of help in the search and rescue operations.”
State television first reported in the afternoon that “an accident happened to the helicopter carrying the president” in the Jolfa region.
“The harsh weather conditions and heavy fog have made it difficult for the rescue teams to reach the accident site,” said one broadcaster, as the massive search effort later continued into the night.
Iran’s Red Crescent chief Pirhossein Koolivand told state TV the area of the accident “has yet to be identified” and that the situation remained “difficult”.
Interior Minister Ahmad Vahidi said the helicopter “made a hard landing” in bad weather and that it was “difficult to establish communication” with the aircraft.
He urged people to get their information “only from state television”, and not listen to foreign media channels Iran deems hostile to the Islamic republic.
– Massive search effort –
Iran’s cabinet held an emergency meeting led by Vice President Mohammad Mokhber after the incident, IRNA reported.
Raisi’s convoy had included three helicopters, and the other two had “reached their destination safely”, said the Tasnim news agency.
More than 60 rescue teams using search dogs and drones were sent to the mountainous protected forest area of Dizmar near the town of Varzaghan, the IRNA news agency reported.