IRAN's president is feared dead after his helicopter crashed during bad weather.
Aides have warned controversial leader Ebrahim Raisi's "life is at risk" as he remains missing - despite reports the wreckage had been found.
He was travelling in a convoy of three choppers in thick fog when his craft vanished off the radar earlier on Sunday.
The incident was reported to have happened near Jolfa - a city on the border with Azerbaijan, some 375 miles northwest of Tehran.
Reuters news agency quoted state media as saying Raisi's chopper was discovered by search and rescue teams.
It did not detail where it was found, or if any survivors have been located.
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But moments later, Iran's Red Crescent denied the report.
It comes after an Iranian official confirmed contact had been made with one of the passengers and one of the crew members of the President's helicopter on several occasions amid the search.
Raisi, 63, had been at the Azerbaijani border just hours before the crash to inaugurate the Qiz-Qalasi Dam.
The governor of East Azerbaijan province and Foreign Minister Hossein Amir Abdollahian were among the passengers travelling alongside Raisi.
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Their chopper was one of three in a convoy - with the other two helicopters landing safely at their destination.
State TV has stopped all regular programming to air prayers for the president while his whereabouts remains unknown.
It has also broadcast footage showing Raisi in a helicopter earlier on Sunday, prior to the crash.
An Iranian official said the lives of Raisi and his foreign minister - who was also on board - are "at risk".
"We are still hopeful but information coming from the crash site is very concerning," the official said.
Russian President Vladimir Putin has ordered the deployment of two aircraft and 50 rescue personnel to Tabriz as part of the search effort, according to reports.
'DOESN'T BODE WELL'
Former UK defence minister Tobias Ellwood told Sky News: "It doesn't bode well when it takes so long to get in touch with what's happened."
He added that a lack of information from Iranian state media is concerning.
The Tory MP said: "If the president was alive, it would confirm it straight away, but if he has died then they may be delaying any announcement to ensure contingency plans are in place."
He added the potential death of Riasi could mean there are "huge geopolitical consequences for Iran".
Iranian state media said bad weather was the cause of the crash and had complicated rescue efforts, with a rescue helicopter unable to land.
Search efforts have reportedly been concentrated around a copper mine where visibility is currently less than five metres.
At least 40 rescue teams have been deployed to the crash site.
Footage showed cars speeding to the site in thick fog - and a search party on foot was seen searching for the helicopter, with ambulances and rescue vehicles lined up nearby.
The chief of staff of Iran's army ordered all the resources of the army and the elite Revolutionary Guard to be put to use in search and rescue operations.
"It is dark and it has started raining, but the search continues," a local reporter told state TV.
"Rescue teams have reached the area ... however, the rain has created mud, making the search difficult."
The European Union says it has activated its rapid response mapping service, known as Copernicus, to help with the search for the crashed helicopter.
The Copernicus system provides mapping products based on satellite imagery.
Footage reportedly shows members of the Islamic Revolutionary Guard Corps' Saberin Special Forces preparing to enter a forested area as part of the search.
Iran's interior minister, Ahmed Vahidi, said Raisi was on his way back from the inauguration event "when the helicopter carrying him had a hard landing due to the foggy weather in the area".
Rescuers have resorted to using drones in a bid to locate the missing helicopter.
Mr Vahidi said the rescue operation "will take time".
He told state TV: "Efforts are underway, and we hope to reach a resolution soon.
“It’s a complicated area, and making contact is difficult. We are waiting for teams to reach the area for more information."
The US State Department said it is "closely watching" reports of the crash.
A spokesperson for President Joe Biden, Karine Jean-Pierre, told reporters aboard Air Force One that the president had been briefed on the situation. She did not elaborate.
Azerbaijan's President Ilham Aliyev, who said he had bid a "friendly farewell" to Raisi earlier in the day, offered assistance in the rescue. Neighbour Iraq also offered help, as has Russia and Turkey.
Iran flies a variety of helicopters but struggles to obtain new parts for them because of international sanctions.
The country's military air fleet also dates back to before the Islamic revolution of 1979.
GROWING DISSENT
The crash comes at a time of growing dissent within Iran over an array of political, social and economic crises.
Footage even shows people setting off fireworks, reportedly in response to news of the crash.
Iran's clerical rulers face international pressure over Tehran's disputed nuclear programme and its deepening military ties with Russia during the war in Ukraine.
Since Iran's ally Hamas attacked Israel on October 7 provoking Israel's assault on Gaza, conflagrations involving Iran-aligned groups have erupted throughout the Middle East.
Raisi secured a victory during the 2021 presidential election, which saw the lowest turnout in the country's history.
What happens if an Iranian president is incapacitated or dies in office?
Below is a brief outline of what Iran's constitution says happens if a president is incapacitated or dies in office:
* According to article 131 of the Islamic Republic's constitution, if a president dies in office the first vice president takes over, with the confirmation of the supreme leader, who has the final say in all matters of state.
* A council consisting of the first vice president, the speaker of parliament and the head of the judiciary must arrange a election for a new president within a maximum period of 50 days.
Ebrahim Raisi was elected president in 2021 and, under the current timetable, presidential elections are due to take place in 2025.
Since taking office he has ordered a tightening of morality laws, overseen a bloody crackdown on anti-government protests and pushed hard in nuclear talks with world powers.
He is sanctioned by US for his involvement in a massacre of thousands of political activists in 1988 as the bloody Iran-Iraq war neared its end.
Under his rule, Iran has ramped up its uranium production at nearly nuke-grade level and obstructed international inspections.
Iran has also been supplying Putin's illegal war in Ukraine and backed Houthi rebels who have spent months waging war on commercial shipping in the Red Sea.
It comes weeks after Iran unleashed an unprecedented drone-and-missile attack on Jerusalem which was branded "a declaration of war" by Israel.
More than 300 drones and missiles were launched at Israel by Iran and its proxy groups in Lebanon and Yemen - 99 per cent of which were intercepted, according to the Israeli military.
DUAL POLITICAL SYSTEM
In Iran's dual political system, split between the clerical establishment and the government, it is Raisi's 85-year-old mentor Ayatollah Ali Khamenei, supreme leader since 1989, who has the final say on all major policies.
For years many have seen Raisi as a strong contender to succeed Khamenei, who has endorsed Raisi's main policies.
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Raisi's victory in a closely managed election in 2021 brought all branches of power under the control of hardliners, after eight years when the presidency had been held by pragmatist Hassan Rouhani and a nuclear deal negotiated with Washington.
However, Raisi's standing may have been dented by widespread protests against clerical rule and a failure to turn around Iran's economy, hamstrung by Western sanctions.