A local official told state TV: "There were no fatalities and nearby villages have been evacuated as a safety measure ... part of the gas pipeline ... exploded near Gonaveh ... No dead has been reported."
Four workers were injured and were transferred to nearby hospitals, he added.
Another official said a crisis management headquarter had been set up in Gonaveh.
"The pipeline has been disconnected from the system ... the fire will be fully ... under control as soon as the gas inside the pipeline is evacuated," the semi-official Fars news agency quoted the official as saying.

