The United States sees no "proliferation risk" from Iran's nuclear power plant at Bushehr that was loaded with Russian fuel on Saturday, the State Department said.

The Russian involvement in the reactor, intended for civilian purposes, "underscores that Iran does not need an indigenous enrichment capability if its intentions are purely peaceful," State Department spokesman Darby Holladay said.

"We recognize that the Bushehr reactor is designed to provide civilian nuclear power and do not view it as a proliferation risk," he said.

Israel denounced Iran's fueling up of its first nuclear power plant as "totally unacceptable" and called for more international pressure to force Tehran to cease any uranium enrichment.

However, Israel, widely assumed to be the only Middle East country to have nuclear weapons, has said a nuclear-armed Iran would be a threat to its existence, raising concerns Israel could attack Iran's nuclear sites.

In a statement issued after the Islamic Republic celebrated the launch of its reactor in Bushehr, Israeli Foreign Ministry spokesman Yossi Levy said: "It is totally unacceptable that a country that so blatantly violates resolutions of the (United Nations) Security Council, decisions of the International Atomic Energy Agency and its commitments under the NPT (non-proliferation treaty) should enjoy the fruits of using nuclear energy."    

"The international community should increase pressure on to force Iran to abide by international decisions and cease its enrichment activities and its construction of reactors," Levy said.

The United States, Israel and some other Western countries fear Iran's nuclear is aimed at produce atomic weapons. Iran says it wants nuclear power solely for energy production.