Rosatom spokesman Sergei Novikov said Friday that uranium fuel shipped by Russia will be loaded into the Bushehr reactor on Aug. 21, beginning the startup process.
"From that moment the Bushehr plant will be officially considered a nuclear-energy installation," he told The Associated Press.
The United States has called for Russia to delay the startup until Iran proves that it's not developing nuclear weapons. Russian officials said that the latest U.N. sanctions against Iran won't affect the Bushehr project.
Russia signed a $1 billion contract in 1995 for building the Bushehr plant, but it has dragged its feet on completing the project for years.
Moscow has cited technical reasons for the delays, but analysts say Moscow has used the project to press Iran to ease its defiance over its nuclear program.
Novikov said that Rosatom chief Sergei Kiriyenko will travel to Bushehr in southern Iran for the Aug. 21 ceremony, which will also be attended by the Iranian Vice President Ali Akbar Salehi, who also heads the Atomic Energy Organization of Iran.
Prime Minister Vladimir Putin said in March that the Bushehr plant would begin operating this summer. Some Iranian lawmakers have accused Russia of delaying the project under the Western pressure.