The 13th International Oil, Gas and Petrochemical Exhibition opened here Wednesday.
Iran's Oil Minister Gholam-Hossein Nozari was present at the opening ceremony of the exhibition slated for April 16-20.
Some 505 foreign and 860 Iranian companies are participating in the fair, local Press TV satellite channel reported.
The foreign participants from 30 countries, including China, are active in the fields of oil, natural gas and petrochemical industries.
Last exhibition, held in April 2007, attracted over 1,250 companies at home and abroad as well as 103,000 visitors.