Tehran, Feb 18 (AP): An Iranian commercial plane crashed today in a foggy, mountainous region of southern Iran, killing all 66 people on board, state media reported.

An Aseman Airlines ATR-72, a twin-engine turboprop used for short-distance regional flying, went down near its destination of the southern Iranian city of Yasuj, some 780 kilometers south of the Iranian capital, Tehran.

Aseman Airlines spokesman Mohammad Taghi Tabatabai told state TV that all on the flight were killed. The plane carried 60 passengers, including one child, and six crew members.

Due to foggy condition, rescue helicopters couldn't reach the crash site in the Zagros Mountains, state TV reported.

Tabatabai said the plane crashed into Mount Dena, which is about 440-meters tall.

Aseman Airlines is a semi-private air carrier headquartered in Tehran that specialises in flights to remote airfields across the country. It also flies internationally.

The Iranian Red Crescent said it has deployed to the area. Authorities said they would be investigating.

Under decades of international sanctions, Iran's commercial passenger aircraft fleet has aged, with air accidents occurring regularly in recent years.

Following the 2015 landmark nuclear deal with world powers, Iran signed deals with both Airbus and Boeing to buy scores of passenger planes.