Iran has launched a test run of its first Russian-built nuclear power plant in the southwestern city of Bushehr, Iranian officials say.
Mohsen Shirazi, a spokesman for Iran's atomic energy agency, said Sergei Kiriyenko, the visiting head of Russia's state nuclear agency, and Gholam Reza Aghazadeh, his Iranian counterpart, visited the plant on Wednesday to inspect the work.
Shirazi said the comprehensive tests of various equipment at the 1,000-megawatt plant included injecting "virtual" fuel, instead of nuclear fuel, into rods at the plant.
The fuel is made of lead and is designed to imitate enriched uranium needed to run the nuclear reactor.
Kiriyenko said construction of the plant was now complete.
"The construction stage of the nuclear power plant is over, we are now in the pre-comissioning stage, which is a combination of complex procedures," he told reporters.
Russia assisted Iran in the construction of the Bushehr plant in a $1bn contract, though Iran had complained of delays.
Russia attributed the delays to payment disputes, although analysts say Moscow was unhappy with Iran's resistance to international pressure to make its nuclear programme more transparent.
Iran says its nuclear programmes are for peaceful purposes. However, the West has accused Tehran of covertly attempting to develop nuclear weapons.
Russia has resisted attempts by the West to impose harsher sanctions on Iran.
However, it has also repeatedly urged Tehran to co-operate with the International Atomic Energy Agency, the UN's nuclear agency.