TEHRAN — Iran's first nuclear power plant has been hooked up to the national grid supplying 60 megawatts of its 1,000 megawatt capacity, the country's Atomic Energy Organisation announced on Sunday.

"Last night at 11:29 pm (1859 GMT), the Bushehr power plant was connected with 60 megawatts to the national grid," the organisation's spokesman Hamid Khadem Qaemi, told Al-Alam television.

The connection of the Russian-built plant in southern Iran to the national grid was originally scheduled for the end of 2010.

The Bushehr plant was started up in November 2010 but repeated technical problems delayed its operations, leading to the removal of its fuel rods last March.

"The capacity will gradually increase and it (is going through its) testing phase and on Shahrviar 21 (September 12) in a ceremony the power plant will reach its 40-percent capacity," Khadem Qaemi said.

The deputy atomic chief in charge of power plants, Mohammad Ahmadian, told state television the plant was expected to reach full capacity at "around the end of Aban or beginning of Azar (November)."

"But it is very important for us to take these final steps with utmost safety concerns in mind. We want to have guaranteed functional operation," Ahmadian added.

In mid-August, Iran's atomic organisation chief Fereydoon Abbasi Davani said the plant was expected to reach "full capacity of 1,000 megawatts" in late November or early December.

Russia, which built the plant, has pinned the delays on Iran, saying its engineers have been forced to work with outdated parts. The latest delay in March was blamed on wear and tear at the plant.

Construction started in the 1970s with the help of German company Siemens, which quit the project after the 1979 Islamic revolution over concerns about nuclear proliferation.

In 1994, Russia agreed to complete the plant and provide fuel for it, with the supply deal committing Iran to returning the spent fuel to allay Western concerns over its nuclear ambitions.

Western governments suspect Iran is seeking an atomic weapons capability under the guise of its civilian space and nuclear programmes, a charge Iran vehemently denies.

Iran on Friday welcomed as a "step forward" an International Atomic Energy Agency (IAEA) report on its nuclear activities, saying it highlighted positive steps taken by Tehran towards "cooperation and transparency."

But the UN atomic watchdog said in a confidential report, a copy of which was obtained by AFP on Friday, that it was "increasingly concerned about the possible existence in Iran of past or current undisclosed nuclear related activities involving military related organisations."

These included "activities related to the development of a nuclear payload for a missile", according to the report, which is due to be discussed by the IAEA's 35-member board of governors at a September 12-16 meeting.