Key points
- A helicopter carrying Iran's president involved in hard landing during bad weather
- Contact made with passenger and crew member, says official
- Lives 'at risk' after incident, says Iranian official
- Rescuers head to site - but fog and rain causing problems
- Last-known picture of helicopter carrying president released
- Here's what we know so far
- Alistair Bunkall: Flow of information is being tightly controlled - but there might be an encouraging sign soon
- Live reporting by Jess Sharp
Turkish drone locates heat source in Iranian mountains
A Turkish drone has located a heat source in the Iranian mountains they believe could be the location of the helicopter crash site.
News agency Anadolu reported that the coordinates of the source had been shared with the Iranian authorities.
Iranian foreign ministry thanks 'governments and nations for solidarity'
The Ministry of Foreign Affairs of the Islamic Republic of Iran has issued a statement: "On Sunday afternoon, a helicopter carrying the President, the Minister of Foreign Affairs, and several companions unfortunately had an accident in the Varzaghan region of East Azerbaijan province.
"Despite adverse weather and environmental conditions, efforts by rescue teams to reach the accident site continue earnestly and with hope.
"The Islamic Republic of Iran sincerely thanks the numerous governments, nations, and international organisations for their expressions of human emotion and solidarity with the government and people of Iran, as well as their offers of help and assistance for the search and rescue operation."
Location of helicopter still unknown
Iran is entering the early hours of the morning and the location of the crashed helicopter is still unknown.
Search and rescue teams have been scouring Varzaqan in the East Azerbaijan Province for hours despite heavy rain and fog.
State media outlet IRNA called the area a forest and it is known to be mountainous as well.
It also aired images of SUVs racing through a wooded area and said they were being hampered by poor weather conditions.
A rescue helicopter tried to reach the area where authorities believe the helicopter is, but it couldn't land due to heavy mist, emergency services' spokesman Babak Yektaparast told IRNA.
Late in the evening, Turkey's defence ministry announced that it had sent a drone to help and was also preparing to send a helicopter with night vision capabilities.
How have countries reacted?
We have heard from several countries throughout the day as news of the Iranian president's helicopter crash spread.
Russia, Iraq and Qatar have made formal statements of concern about Ebrahim Raisi's fate and offered to assist in the search operations.
The President of AzerbaijanIlham Aliyev said he was "deeply concerned" to hear of the incident.
He also said his country was ready to provide any support necessary.
Saudi Arabia, which is traditionally a rival of Iran, expressed its concern in a statement and said it "stands by Iran in these difficult circ*mstances".
There was no immediate official reaction from Israel.
In pictures: People pray for Iranian president
In downtown Tehran, crowds of people have gathered to pray for the safe return of the Iranian president.
A ceremony has been held at Vali-e-Asr square and state media has been broadcasting prayers since this afternoon.
Images of hundreds of people, some with their hands outstretched, praying at Imam Reza Shrine in the city of Mashhad, one of Shiite Islam's holiest sites, as well as in Qom and other locations across the country have also been shown.
Here are some of the latest:
Analysis: What's the view from the US?
By Mark Stone, US correspondent
The US president is on the campaign trail this weekend - in Georgia this morning and then Michigan - but his press secretary, Karine Jean-Pierre, has confirmed that he's been briefed on the helicopter crash in Iran.
It's likely statements will have been drafted in preparation for any announcements from Tehran.
A moment like this will make the administration in Washington anxious.
Succession within the opaque political and religious structures of the Islamic Republic is fraught with complications and unknowns.
Supreme Leader Ali Khamenei is the constitutional commander-in-chief, but there would be a scramble underneath him in the event of President Raisi's death or incapacitation.
Raisi has been widely tipped as the most likely to take over from Khamenei as supreme leader.
State Department officials will be dusting off and updating official briefings on Mohammad Mokhber, the vice-president who would, in the short term, succeed Raisi.
The Americans will be watching closely too for any word on contenders for foreign minister.
Ali Bagheri Kani, as the current political deputy at the foreign ministry, is a likely contender.
From a US perspective, he is well-known because he was Iran’s top nuclear negotiator and heled the negotiations in the 2023 prisoner swap/oil asset release deal with the United States.
A relationship of sorts exists between the White House's Middle East and North Africa national security coordinator, Brett McGurk, and Ali Bagheri Kani.
America and Iran do not have any formal diplomatic relations. Their embassies in their respective capitals are mothballed.
But quiet contact is made from time to time, often via their missions at the UN in New York.
Recap: Here's what we know so far
It's nearing midnight in Iran, and there's still no sign of Ebrahim Raisi or foreign minister Hossein Amirabdollahian.
Search and rescue operations are now battling against poor weather conditions and darkness to find the crashed helicopter and any survivors.
If you are just joining us, here's a reminder of what we know so far:
The Iranian president, Mr Amirabdollahian, the governor of Iran's East Azerbaijan province and other officials and bodyguards were on board the helicopter when it crashed.
They were travelling back from a trip to Iran's border with Azerbaijan to inaugurate a dam with Azerbaijan's President Ilham Aliyev.
Two other helicopters were travelling as part of the convoy and made it back safely to their destination.
Initially, state media said the president's chopper was forced to perform a "hard landing" near Jolfa, about 375 miles (600km) northwest of Tehran, but then put it further east near the village of Uzi.
The cause of the crash remains unclear, but initially interior minister Ahmad Vahidi said it was due to "bad weather and fog".
Search teams still trying to find exact crash site
About 40 search teams have been on the ground in the area despite challenging weather conditions.
The search is being done by teams on the ground, as "the weather conditions have made it impossible to conduct aerial searches" via drones,president of the Iranian Red Crescent Society, Pir-Hossein Koulivand, told state media.
Conflicting reports have emerged, with some suggesting the helicopter has been found and others denying that is the case.
Contact made on 'several occasions'
Just before 7pm UK time, an official told state media that contact had been made on several occasions with a passenger and a crew member, but we haven't had any further updates.
Countries offer to help
Several countries, including Iraq, Turkey, Russia and the UAE, have offered to help Iran with its search and rescue operation.
The European Commission has also activated its rapid response satellite mapping service to help the search.
Hamas release statement after 'painful incident'
Hamas has released a statement following the Iranian president's helicopter crash.
The militant group, which is based in Gaza but backed by Iran, said it was following reports of the incident with "great concern".
Describing the incident as "painful", it said it was in "complete solidarity" Iran.
"We ask the God Almighty to protect the Iranian president and his accompanying delegation and to keep the brotherly Iranian people away from all harm and evil," it added.
Analysis: The 'butcher of Tehran' has a fearsome reputation - and many will be fearing instability
By Dominic Waghorn, international affairs editor
Ebrahim Raisi has been one of Iran's hardest of hardliners, a fanatical and absolute believer in the Iranian revolution and its mission.
If he has died on a mountainside in the north of the country, as looks increasingly likely, it will be a major moment for the country and the region.
It will remove from the Middle East one of its toughest most uncompromising players.
A man who launched the first direct attack on Israel in his country's history and a hardliner on whose watch hundreds of Iranians have been killed in the brutal repression of recent women-led protests, Mr Raisi has a huge amount of blood on his hands.
His fearsome reputation goes back to the 1980s - a period that earned him the dubious soubriquet the Butcher of Tehran.
He sat on the so-called Death Panel of four Islamic judges who sentenced thousands of Iranian prisoners of conscience to their deaths during the purge of 1988.
Mr Raisi has personally been involved in two of the darkest periods of Iranian repression. And he was seen as one of the favourite contenders to replace the elderly and ailing Supreme Leader Ali Khamenei.
His accession to that role would have guaranteed years more of the same... and years more meddling abroad.
With Mr Raisi as president, Iran has engaged in more and more adventurous interventions beyond its borders.
With him in charge Iran has helped Houthis menace international shipping in the Red Sea; helped Hezbollah engage Israel in a seven-month duel over its northern border; aided militia in Iraq to attack, and in some cases kill, American soldiers; and helped Hamas fight its own war against the Jewish state.
After two years of unrest, economic failure and stuttering recovery from the pandemic, Iran is divided and weakened.
Its government has lost much of its credibility and support because of the atrocities it has meted out to its women.
Few outside the regime and its ranks of ardent followers will mourn a man who has overseen the death, incarceration or torture of so many.
Iranians may dare yearn for less repressive times without him. Outsiders will hope for a less troublesome Iran.
But there are plenty more where he came from and the Supreme Leader is likely to find another hardliner to replace him.
The fear will be of instability in the run-up to elections. The government has been undermined by recent events, its Supreme Leader is unwell.
If Mr Raisi is dead, his government will try to secure the succession as quickly and smoothly as it can.
In pictures: Latest scenes from the search site
Here are some of the latest photos from the helicopter search site in Varzaqan, East Azerbaijan Province...
