What happens if an Iranian president dies in office?

Rescuers in Iran were racing on Sunday to find the crash site of a helicopter that was carrying President Ebrahim Raisi to find out the fate of all those on board.

Below is 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.

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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.

Raisi was elected president in 2021 and, under the current timetable, presidential elections are due to take place in 2025.