"The earthquake had no effect on the activity of the plant," Mahmoud Jafari, project manager at the Russian-built Bushehr nuclear plant, said according to the Telegram news channel of Iran's state television.

The University of Tehran's seismology centre said the epicentre of the earthquake that hit at 0634 GMT was in the sparsely populated Kaki region, around 80 kilometres (50 miles) from the Bushehr plant.

The head of emergency services said no one was killed or wounded in the quake, media reported.

Bushehr has a 1,000 megawatt reactor built by Russia that became operational in 2011 and reached full capacity the following year.

Iran sits atop several fault lines and has been hit by a series of earthquakes since November 2017, when a 7.3-magnitude tremor killed 620 people in the western province of Kermanshah and eight in Iraq.