The tremor hit the city of Torbat-e Heydariyeh, about 700 km east of Tehran, at 6:20 p.m. (1350 GMT) on Friday, and had its epicenter around 7 km outside the city.

Many people spent the night outdoors in the city's parks fearing aftershocks.

Of the 274 injured, 22 needed hospital treatment while the others were treated on site.

No deaths were reported.

Earthquakes are common in Iran. In 2003, about 30,000 people were killed in a quake that devastated the southeastern city of Bam.