A helicopter carrying Iranian President Ebrahim Raisi has reportedly crashed, according to Iran's state-run IRNA news agency, which initially reported the aircraft had to make an "emergency landing".

"Unconfirmed reports say the helicopter carrying President Raisi has crashed in East Azarbaijan province", IRNA reported.

The incident involving the aircraft carrying Ebrahim Raisi occurred near the city of Jolfa, some 600 km northwest of the capital Tehran.

The helicopter was one of three carrying the president and his entourage, according to local media.

Rescue teams were initially dispatched to the area, with 16 teams involved in the search. However, according to Iran's emergency services, there are now 40 teams involved. Helicopter searches remain impossible because of bad weather.

A senior Iranian government official, who declined to be identified, told Reuters news agency that the lives of the president and foreign minister are "in danger following the helicopter crash".

"We are still hopeful, but the news coming from the crash site is very worrying," he said.

Raisi had been in Azerbaijan earlier on Sunday to inaugurate a dam with his Azeri counterpart, Ilham Aliyev, in what was the third dam built by the two countries on the Aras river.

Iran's interior minister has said that access to the crash site is taking time. Thick fog and poor visibility are hampering efforts to reach the scene, state TV reported.

Other officials on board the helicopter included the governor of East Azerbaijan province and Foreign Minister Hossein Amir Abdollahian.

Iran operates a variety of helicopters, but international sanctions make it difficult to obtain spare parts for them. Its military air fleet also largely dates back to before the 1979 Islamic Revolution.

Raisi, 63, is a hardliner who previously headed the country's judiciary and is seen as a protégé and possible successor to Iran's Supreme Leader Ayatollah Ali Khamenei.

Raisi won Iran's 2021 presidential election, a vote that saw the lowest turnout in the history of the Islamic Republic.

[News updated at 17:19]

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