TEHRAN — Search-and-rescue workers continued to scour a mountainous region of Iran on Monday for a plane that crashed a day earlier, most likely killing all 66 people on board.

Because of bad weather conditions, the rescue teams have been unable to fly over the crash site in helicopters. Instead, they have climbed Mount Dena, which has an elevation of about 14,500 feet. As of Monday afternoon, the teams had not found any debris from the plane, which was operated by Iran Aseman Airlines.

Abbas Ahmad Akhoundi, the minister of roads and urban development, said on Monday that there was “total ambiguity” surrounding the crashing of the plane, an ATR-72 twin-engine turboprop used for short regional flights, which was en route to the southwestern city of Yasuj from Tehran on Sunday morning.