"We are moving according to schedule," Sergei Kiriyenko, head of Rosatom, Russia's state nuclear corporation, said Thursday.
The construction of the Bushehr nuclear power plant was started in 1975 by German companies. However, the German firms stopped work after the imposition of a U.S. embargo on high technology supplies to Iran, RIA Novosti reported.
Russia signed a contract with Iran to finish work on the plant in February 1998. The Bushehr project was originally scheduled for commissioning at the end of 2006, but the date has been postponed several times. Russia has cited financial problems for the delay.
Iran insists it needs its nuclear program to provide civilian energy.
Iran's Atomic Energy Organization said earlier the Bushehr plant was 94.8 percent complete. Foreign Minister Manouchehr Mottaki said the reactor was due to be put into operation in the first half of 2009.