MOSCOW – Russia announced Friday it will begin the startup of Iran’s only atomic power plant next week, giving Tehran a boost as it struggles with international sanctions.

Uranium fuel shipped by Russia will be loaded into the Bushehr reactor on Aug. 21, beginning a process that will last about a month and end with the reactor sending electricity to Iranian cities, Russian and Iranian officials said.

“From that moment, the Bushehr plant will be officially considered a nuclear energy installation,” said Sergei Novikov, a spokesman for the Russian nuclear agency.

If Russia carries out its plan, it will end years of foot-dragging. While Moscow signed a $1 billion contract to build the plant in 1995, its completion has been put off for years.

Moscow has cited technical reasons for the delays. But Bushehr has also been an ideal way to gain leverage with both Tehran and Washington.

Delaying the project has given Russia continued influence with Tehran in international attempts to have it stop uranium enrichment — a program Iran says it needs to make fuel for an envisaged reactor network but which also can be used to create fissile warhead material. The delays also have served to placate the U.S., which opposes rewarding Iran while it continues to defy the U.N. Security Council with its nuclear activities.

After Russia said in March that Bushehr would be launched this year, U.S. Secretary of State Hillary Rodham Clinton said that until Iran reassures the world it is not trying to build a nuclear weapon, “it would be premature to go ahead with any project at this time.”

Formally, the U.S. has no problem with Bushehr.

Although at first opposed to Russian participation in the project, Washington and its allies agreed to remove any reference to it in the first set of Security Council sanctions passed in 2006 in exchange for Moscow’s support for those penalties. Three subsequent sanctions resolutions also have no mention of Bushehr.

The terms of the deal commit the Iranians to allow the Russians to retrieve all used reactor fuel for reprocessing. Spent fuel contains plutonium, which can be used to make atomic weapons. Additionally, Iran has said that International Atomic Energy Agency experts will be able to verify that none of the fresh fuel or waste is diverted.

Still, the U.S. sees the Russian move as a false signal to Tehran as Washington strives to isolate Iran politically and economically to force it to compromise on enrichment.

Russia argues that the Bushehr project is essential for persuading the Islamic Republic to cooperate with the U.N. nuclear watchdog and fulfill its obligations under international nuclear nonproliferation agreements.

Russian officials did not say why they had decided to move ahead with loading fuel into the Bushehr plant now. But the move could have been triggered in part by Moscow’s desire show the Iranians it can act independently from Washington after its decision to support the fourth set of U.N. sanctions in June and its continued refusal to ship surface-to-air missile systems that it agreed to provide under a 2007 contract to sell the S-300s.