The Iranian Government says it is going ahead with the second phase of its controversial nuclear power plant in Bushehr.
Experts question why resource-rich Iran needs nuclear power
Iran's state news agency Irna said the decision was taken by the country's High Council of Atomic Energy, which did not give a start date for the second phase, but did mention for the first time construction of a particle accelerator.
The United States and Israel accuse Iran of secretly developing nuclear weapons under the cover of a civilian programme, but Tehran insists its programme is to generate electricity and is for peaceful purposes only.
The decision to proceed with the Bushehr project came shortly after experts from the United Nations nuclear watchdog, the International Atomic Energy Agency (IAEA), had held talks in Iran to demand snap inspections of its nuclear sites.
Allows for inspections at short notice
IAEA can take environmental samples at any location
The European Union, Russia and Japan are pressing Tehran to sign up the so-called additional protocol of the Nuclear Non-Proliferation Treaty (NPT), allowing such inspections.
But Iran - which presently is only obliged to accept pre-arranged visits to sites it chooses to declare - has previously said it would only agree to such a measure if it was granted more access to nuclear technology.
Bushehr - Iran's first nuclear power plant being built with the help of Russian specialists - is due to go online in 2005.
The second phase is expected to have a production capacity of 1,000 megawatts, allowing Iran to reach its nuclear power production target of 7,000 megawatts by 2020, IRNA said.
Nuclear experts have questioned the declared need of Iran - a country with vast oil and natural gas reserves - to produce nuclear energy.