The 5.6-magnitude quake hit 715km east of Tehran and was centered 26.1km deep, the US Geological Survey said.

The agricultural city of Torbat-e Heydarieh, at the epicenter, was rocked for about 10 seconds, the Islamic Republic News Agency (IRNA) reported. Most of the damage was seen in the surrounding 70 villages outside the city, some of which saw roughly half their houses affected, IRNA said.

Twelve people have been critically injured and hospitalized, IRNA reported. Police were attempting crowd control at the hospital in Torbat-e Heydarieh, which was packed with people searching for loved ones.

The Red Cross and local government agencies were responding with medical supplies, tents, food and water, IRNA reported.

The news agency said the city has already reported scores of livestock deaths from July 30 quake.

Iran lies on a series of seismic fault lines and has experienced devastating earthquakes - most notably in December 2003, when a 6.6-magnitude quake devastated the ancient city of Bam in southeast Iran, killing at least 30,000 people.

Last year, an earthquake struck Hormozgan province in southern Iran, injuring about 700 people in the port city of Bandar Abbas, state-run media reported.

In 2008, a strong earthquake measuring 6.1 in magnitude struck in Hormozgan, demolishing nearly 200 villages and killing at least six people.