The Iranian cabinet has convened for an emergency meeting in light of the helicopter accident involving President Ebrahim Raisi and Foreign Minister Hussein Amirabdollahian, state media reported Sunday.
The first vice president, Mohammad Mokhber, chaired the meeting in the late evening, state news agency IRNA reported.
He initiated further measures for the rescue operation. According to protocol, Mockber would become president in the event of Raisi's death.
Rescue workers continued to search on foot after dark for the scene of the helicopter accident, in poor weather conditions.
A total of 65 rescue teams were involved in the search for the helicopter's crew, including the Iranian armed forces.
According to the Tasnim news agency, the accident site has been located.
The Iranian government asked the rescue services in neighbouring Turkey for assistance in the search. Both Turkey and Russia had offered their help.
In particular, helicopters with night vision equipment were requested.
Meanwhile, special mountain rescue units also arrived in the accident region, IRNA reported.
The the Iranian president's helicopter came in for what has been called a "hard landing" on Sunday in the north-west of the country after a meeting between Raisi and the president of neighbouring Azerbaijan, Ilham Aliyev.