The Russian Federal Atomic Energy Agency (Rosatom) said earlier on Friday the first reactor at the Bushehr NPP would be loaded with nuclear fuel on August 21.

"The supply of Russian fuel to this reactor is another reason why the Islamic Republic should halt its dangerous nuclear activity in accordance with the UN Security Council resolution," ministry spokeswoman Christine Fages said. "Iran can only use Russian fuel that is specifically adapted to this reactor."

She said Iran's uranium enrichment activity could not be reasonably justified by the Bushehr reactor.

The construction of Iran's first nuclear plant was begun in 1975 by several German construction companies. They pulled out following a U.S. embargo on high-technology supplies to Iran after the 1979 Islamic Revolution and the subsequent U.S. Embassy siege in Tehran.

Russia signed a contract with Iran to complete construction in February 1998.

On June 9, 2010, the UN Security Council approved a fourth round of sanctions against Iran over its nuclear program, including tougher financial controls and an expanded arms embargo, as well as an asset ban on three dozen companies and a travel freeze on individuals.

Later, the United States and the European Union imposed extra unilateral sanctions against Iran, including tougher restrictions on the energy sector and a tougher trade embargo.

The construction of the Bushehr Nuclear Power Plant has not been affected by the sanctions.