Iran and Russia began to load uranium fuel into Iran's first nuclear power plant on Saturday in the wake of Tehran's signal of a possible willingness to compromise on nuclear fuel enrichment, a major concern for the West regarding Iran's nuclear drive.

A general view shows the Bushehr nuclear power plant in southern Iran, Aug. 20, 2010. Bushehr nuclear power plant, the first one in Iran, will begin fuel injection on Aug. 21, after which the power plant will be launched soon. Iran handed over the Bushehr project, started by German firms in the 1970s, to Russia in 1995. The launch of the project has been postponed repeatedly in recent years. [Ahmad Halabisaz/Xinhua]

Nationwide celebrations are planned for the fuel delivery to the first unit of the 1,000-megawatt Bushehr nuclear power plant in southern Iran as the operation will mark a milestone for a nation that is resolved to pursue nuclear program.

The fuel-loading process is expected to take at least a week in Bushehr, about 1,200 km south of Tehran. It will take more than two months before it produces electricity.

Ali Akbar Salehi, head of Iran's Atomic Energy Organization, said earlier that experts from the International Atomic Energy Agency (IAEA) were expected to oversee the transfer of the fuel, which symbolized the beginning of the physical startup of the unit.

The much-anticipated launch marks an end to decades of delay in building the Beshehr nuclear plant. Its construction was started in the 1970s by a German company but was shelved shortly after the Islamic Revolution in Iran in 1979 as the German side pulled out of the deal.

Russia signed an agreement worth 1 billion U.S. dollars in 1995 to take over the project. Its completion, first scheduled for 1999, was postponed several times by mounting technological and financial challenges and interruptions under pressure from the United States.

Under the agreement between Moscow and Tehran, Russia will take back all spent reactor fuel. Experts of the IAEA will be able to verify that no fuel or waste is diverted.

On the eve of the inauguration of Iran's first nuclear power plant, President Mahmoud Ahmadinejad indicated that Tehran would stop higher-grade enrichment if the supply of nuclear fuel for a medical research reactor in Tehran is guaranteed.