Russia has been building the plant for Iran since the mid-90s
Iran's first nuclear power plant will be operating by mid-2010, Iranian and Russian officials say.
The Bushehr plant was begun in 1974 and abandoned five years later. Russia took over building work in the 1990s, but it has been beset with delays.
Iran's semi-official Fars news agency quoted the head of Iran's atomic agency as saying that the plant had passed most tests successfully.
Russia's state nuclear corporation said the reactor would be started this year.
Its chief Sergei Kiriyenko said: "2010 is the year of Bushehr."
He told reporters after a cabinet meeting in Moscow: "There is absolutely no doubt that it will be built this year. Everything is going according to schedule," Reuters news agency reported.
The head of the Atomic Energy Organisation of Iran, Ali Akbar Salehi, said: "We will launch the Bushehr power plant in the first half of the next [Iranian] year [beginning on March 21]," Fars reported.
The timetable comes just two months after the Russian energy minister said that the planned 2010 operation would not be possible.
At the time, analysts linked the delay to political pressure on Iran from Western powers to give up its nuclear weapon ambitions, but Russia said it was for technical issues.
Russia signed a deal with Iran to complete the plant in the 1990s, but it was delayed while the UN Security Council debated and then passed resolutions aimed at stopping uranium enrichment in Iran.
In December 2007, Moscow started delivering the canisters of enriched uranium the plant needs, and in February 2009 a test run was begun.
The test, lasting several months, involved dummy rods that imitate the enriched uranium needed to run the plant.
Any nuclear fuel from the plant will be brought from and returned to Russia so that it cannot be used for a weapons programme.