STORY: A helicopter carrying Iranian President Ebrahim Raisi and his foreign minister crashed on Sunday, an Iranian official told Reuters.

It was crossing mountain terrain in heavy fog on the way back from a visit to the border with Azerbaijan.

The official said the lives of Raisi and Foreign Minister Hossein Amirabdollahian were, quote, "at risk following the helicopter crash."

Iranian state TV stopped all regular programming, showing instead live coverage of rescue teams heading to the crash site on foot in heavy fog.

Raisi had been at the Azerbaijani border to inaugurate the Qiz-Qalaisi Dam, a joint project.

He was elected president at the second attempt in 2021, and since taking office has ordered a tightening of morality laws, overseen a bloody crackdown on anti-government protests and pushed hard in nuclear talks with world powers.

Iran's dual political system is split between the clerical establishment and the government, and it is the supreme leader rather than the president who has the final say on all major policies.

But many see Raisi as a strong contender to succeed his 85-year-old mentor, Supreme Leader Ayatollah Ali Khamenei, who has strongly endorsed Raisi's main policies.

Authorities are awaiting further details on the crash, according to Iran's interior minister.