(Adds comment from oil official)

TEHRAN, March 26 (Reuters) - An earthquake with a magnitude of 5.3 shook a region in southwest Iran on Wednesday but there were no immediate reports of any casualties, the official IRNA news agency reported.

The quake struck in an area round the city of Dogonbadan, about 600 km (375 miles) south of the Iranian capital Tehran, IRNA quoted Iran's Geophysics Institute as saying.

Dogonbadan is situated near some big Iranian oil fields.

"We are not aware of any damage to the oil or gas facilities in the Sardasht region," an official from the National Iranian South Oil Company in Sardasht, a city about 90 km (56 miles) west of Dogonbadan, told Reuters

Iran, the world's fourth largest oil producer, is frequently struck by earthquakes because the country is criss-crossed by faultlines. (Reporting by Hashem Kalantari; Editing by Dominic Evans)

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