After about a half-hour drive on an almost straight road by car from an airport in Assaluyeh on the Persian Gulf coast in southern Iran, high stacks emitting orange flames of burning natural gas begin to come into view against a backdrop of mountains.

The flames tower over huge gas refinery facilities constituting a maze of pipes, valves and storage tanks in the Pars Special Economic Energy Zone, where gigantic petrochemical complexes also sit.

"The height of the tower reaches 140 meters," Morad Dehdari, a PSEEZ tour leader, told reporters who visited the zone in Assaluyeh, about 900 km south of Tehran, where the mercury topped 40 degrees under a scorching sun.