Iran has begun loading fuel at its first nuclear power station in a ceremony attended by Russian officials.
Russia will operate the Bushehr plant in southern Iran, supplying its nuclear fuel and taking away the nuclear waste.
State television showed live pictures of a fuel rod assembly being prepared for insertion into the reactor.
Iran has been subject to four rounds of UN sanctions because of its separate uranium enrichment programme.
The West fears Tehran wants to build a nuclear weapon, but Iran
insists its plans are for domestic energy production.
The BBC reports the Bushehr plant should begin producing electricity in about a month.
Mixed reaction
Israel called the move totally unacceptable and urged world powers to increase pressure on Iran to comply with international decisions and stop its uranium enrichment and heavy water reactor programmes.
But the United States government says the plant does not pose a proliferation risk.
The Bushehr facility has been plagued by delays and has taken 35 years to build.
