Russia has signed a preliminary agreement to build at least two more nuclear power plants in the Iranian port city of Bushehr, AFP reported on Wednesday, citing Iran's official IRNA news agency.
The deal was reached during a visit to Tehran on Tuesday by a senior official of Russia's state atomic energy agency Rosatom, IRNA said.
"Iran and Russia reached a preliminary agreement to build at least two new nuclear power plants," Iranian Atomic Energy Organisation spokesman Behrouz Kamalvandi was quoted as having said.
The two new 1,000 megawatt plants will be constructed alongside the existing power station in Bushehr, which was also built by Russia, Kamalvandi said.
Further talks will be held on technical and financial aspects of the project, but a final agreement is expected to be signed "very soon", he added.
The Islamic Republic signed the Bushehr contract with Russia in 1995 and the nuclear power plant reached its full capacity by August 2012. The plant made headlines this summer when it experienced a critical malfunction, leading some to believe that it had been the result of a cyber attack.
While Iranian officials insist that the plant is only being used for nuclear power, some Western experts have expressed concerns that the plant is capable of producing a nuclear weapon.
In January, Iranian President Hassan Rouhani told his Russian counterpart Vladimir Putin that establishing long-term relations between the two countries "can serve the stability and security of the region."
Iranian media last month speculated that Rouhani could travel to Russia for a regional conference of Caspian Sea states that Tehran's envoy to Moscow has said will be in late September, according to AFP.
In December, Rouhani announced that his country would build a second nuclear power plant in Bushehr.
Construction of the new Bushehr nuclear plants is likely to spark concerns among Gulf Arab states, which have often raised concerns about the reliability of the existing Bushehr facility and the risk of radioactive leaks in case of a major earthquake.
Iran sits astride several major fault lines and is prone to frequent quakes. On April 9, a 6.1-magnitude quake rocked the south, with an epicenter just 100 kilometers (60 miles) from Bushehr.
Both Iran and Russia have dismissed the claim, saying the Bushehr facility is subject to inspection by and the safeguards of the International Atomic Energy Agency (IAEA), the UN watchdog.
Officials in Tehran reassured the international community after recent earthquakes that the facility was undamaged.