Iran's first nuclear power plant, built by Russia, will be connected to the national grid in late August, atomic chief Fereydoon Abbasi Davani told the Arabic-language network Al-Alam on Sunday.
"The test to reach 40 percent of the plant's power capacity has been done successfully... God willing, we will be able to commission the plant by the end of Ramadan with an initial production" of the same amount, Abbasi Davani said.
He estimated that the plant would reach its "full capacity of 1,000 megawatts" in late November or early December.
"We will then organise an official ceremony, for which it has been suggested that Russian President Dmitry Medvedev come to Iran," he said.
The connection of the Bushehr plant in southern Iran to the national grid, originally scheduled for the end of 2010, has been been delayed several times because of technical problems.
The plant was started up in November 2010 but repeated technical problems delayed its operation, leading to the removal of its fuel in March.
Russia has blamed the delays on Iran for forcing its engineers to work with outdated parts in the facility, while the latest delay in March was pinned on wear and tear at the plant.
Construction of the plant started in the 1970s with the help of German company Siemens, which quit the project after the 1979 Islamic revolution over concerns about nuclear proliferation.
In 1994, Russia agreed to complete the plant and provide fuel for it, with the supply deal committing Iran to returning the spent fuel, amid Western concerns over the Islamic republic's controversial uranium enrichment programme.
Abbasi Davani's remarks come on the eve of a scheduled visit by Security Council of Russia's secretary Nikolai Patrushev, who will hold talks with his Iranian counterpart Saeed Jalili and President Mahmoud Ahmadinejad in Tehran.
Meanwhile, Foreign Minister Ali Akbar Salehi will go to Moscow amid Russian efforts to revive talks between Tehran and world powers on Iran's nuclear programme.
Western powers suspect Tehran is seeking an atomic weapons capability under the guise of its civilian space and nuclear programmes, a charge Iran vehemently denies.
Explore further: Running fuel cells on bacteria