CNN. Iran began fueling its first nuclear energy plant in the southern city of Bushehr on Saturday, the nation's state media reported.
The effort will help the country create nuclear-generated electricity, Press TV said.
The transfer of nuclear fuel was being watched by the International Atomic Energy Agency and senior officials from Iran and Russia, Press TV said.
Some Western nations have questioned whether the nuclear fuel will be used solely for electricity or would Iran eventually try to enrich uranium on its own, providing material for nuclear weapons.
It will take about two months for the reactor to begin generating electricity, state media has reported. Russia's nuclear agency says it will take longer.
Ayatollah Ali Khamenei, Iran's supreme leader, recently asserted Iran's right to establish nuclear plants.
Sergei Kiriyenko, general director of Rosatom, the Russian State Atomic Energy Corporation said Saturday's arrival of nuclear fuel marks "an event of crucial importance" that proves that "Russia always fulfills its international obligations."
Spent nuclear fuel from the plant will be sent back to Russia.
The opening of the plant prompted the White House to question Iran continuing to enrich uranium within its borders.
"Russia is providing the fuel, and taking the fuel back out," White House spokesman Robert Gibbs said earlier this month.
"It, quite clearly, I think, underscores that Iran does not need its own enrichment capability if its intentions, as it states, are for a peaceful nuclear program," he said.
Russian Foreign Minister Sergey Lavrov, speaking to Russian reporters in the Black Sea resort of Sochi Wednesday, brushed off Western concerns about the Bushehr facility, calling it "the most important anchor holding Iran to the nonproliferation regime," according to the Russian news agency RIA-Novosti.
The Bushehr facility was originally scheduled to start operations in 2007, but the date for commissioning the plant has been postponed a number of times due to various technical, financial and political factors.