The US Geological Survey says a magnitude 5.5 earthquake has struck in southern Iran near a nuclear plant, shaking Bahrain and other areas around the Persian Gulf. There was no immediate report of damage or injuries.
The USGS says the quake struck at 0634 GMT some 100 kilometres, about 60 miles, east of Bushehr.
Iranian state television, citing officials, described the quake as a magnitude 5.9. Varying magnitudes are common immediately after a temblor.
In Bahrain, an island kingdom off Saudi Arabia, people on social media said they felt the quake and evacuated from high-rise buildings.
Iran sits on major fault lines and is prone to near-daily earthquakes.In 2003, a 6. 6-magnitude quake flattened the historic city of Bam, killing 26,000 people.