Iran on Monday confirmed that President Ebrahim Raisi died when his helicopter crashed in a mountainous northwestern region on Sunday.

"The president of the Islamic Republic of Iran, Ayatollah Ebrahim Raisi, had an accident while serving and performing his duty for the people of Iran and was martyred," Iran's Mehr agency said as other media outlets also reported the news. 

The Iranian government said it will continue to operate "without the slightest disruption."  

"We assure the loyal nation that the path of service will continue with the tireless spirit of Ayatollah Raisi without the slightest disruption,"  the government said in a statement.

The Iranian Red Crescent said the bodies of President Raisi and others who died in the helicopter crash had been recovered, and search operations had ended.

"We are in the process of transferring the bodies of the martyrs to Tabriz" in Iran's northwest, Red Crescent chief Pirhossein Koolivand told state TV, adding that "the search operations have come to an end." 

On Sunday, Iranian state television reported that a helicopter carrying Raisi had been in an accident in the Jolfa region of East Azerbaijan province amid poor weather conditions.

The accident happened in the mountainous protected forest area of Dizmar near the town of Varzaghan, according to the official IRNA news agency.

Early Monday, Iran's Red Crescent chief Pirhossein Koolivand said rescue teams had located the helicopter and were heading towards the site. 

State TV reported that there were "no signs" of life among passengers "as of yet." 

Local media has shared multiple images of what appeared to be the wreckage of the aircraft.

Raisi had earlier inaugurated a dam project with his Azeri counterpart, Ilham Aliyev, on the border between the two countries.  

Iran's Interior Minister Ahmad Vahidi described the accident as a "hard landing due to the weather conditions".

Raisi's convoy comprised three helicopters including two that landed safely in the northwestern city of Tabriz. 

Vahidi said it was "difficult to establish communication" with the third helicopter which was carrying Raisi. 

Foreign Minister Hossein Amir-Abdollahian was also on board along with the governor of East Azerbaijan and the province's main imam, according to IRNA news agency. 

- How has Iran responded? -

A total of 73 rescue teams were involved in the search, according to the Red Crescent, with IRNA saying search dogs and drones were being used. 

Military personnel along with the Revolutionary Guards and the police have also been sent to the area, the army's chief-of-staff Mohammad Bagheri said.  

Red Crescent rescue teams were seen on state TV on a steep slope as they attempted approaching the helicopter's location amid thick fog.

Under Iran's constitution, vice-president Mohmmad Mokhber will take over presidential duties.

Presidential elections would then be arranged within 50 days, according to the constitution.