A Tu-154 plane has crashed into mountains near the western Iranian city of Korramabad, reportedly killing all 117 people on board.
The crash has raised concerns on the reliability and safety of ageing Russian built planes. This is the third disaster in a year involving Soviet built aircraft.
In May 2001, all 30 passengers on board a chartered Russian Yak-40 died when it crashed on a flight to the north-east of the country.
Officials blamed the crash on bad weather and pilot error at the time.
Another Tu-154 plane crashed near Irkutsk in Russia last July, killing all 133 passengers and 10 crew members. That crash was the 20th involving a Tu-154 since it entered service in the early 1970s.
This latest accident is now under investigation and an Iran Air official said the plane had disappeared off radar screens south-west of Korramabad, which lies east of Zagros mountain range.
The Iran Air Tours flight was on a routine internal journey from the capital Tehran.
