The 1,000-megawatt Russian-built plant in the southern port city of Bushehr will first generate around 500 megawatts, Foreign Minister Manouchehr Mottaki told parliament, the official IRNA news agency reported.
"Since the fuel for the power plant is in Iran, the project will be operational in the summer (the quarter ending September) and generate 500 megawatts of electricity that would be transmitted to the national grid."
The plant will achieve full capacity in the second half of the Iranian year to March 2010, he said.
Iran and Russian officials began testing the plant on February 25, as Tehran pressed on with its controversial nuclear programme despite Western fears it may be secretly trying to build an atomic bomb.
Moscow supplied the fuel for the plant in 2008 but it is currently sealed by the UN watchdog the International Atomic Energy Agency, which has been investigating Iran's nuclear drive for six years.
Sergei Kiriyenko, the head of Moscow's federal nuclear agency, announced when tests began that construction of the plant was complete but he did not set any date for its commissioning.
The testing of the Bushehr plant raised fresh concerns in the international community over Iran's nuclear development, although Tehran insists that its atomic programme is purely peaceful.
On Tuesday, the five permanent members of the UN Security Council and Germany said in a rare joint statement that they were ready for direct talks with Iran to resolve the long-running nuclear standoff.
Despite being the world's number four crude oil producer and holding the second largest gas reserves, Iran insists it needs nuclear power to sustain a growing population, saying its fossil fuel will run out in the coming decades.
