Russia's nuclear energy agency says the order to remove fuel from the Russian-built nuclear plant in Iran came because of concerns that metal particles might be contaminating fuel assemblies.
The Saturday announcement that fuel would be unloaded from the Bushehr plant was seen as a setback for Iran's nuclear program and raised questions about whether the mysterious computer worm known as Stuxnet might have caused more damage at the plant than previously acknowledged.
Foreign intelligence reports have said the control systems at Bushehr were penetrated by the malware _ malicious software designed to infiltrate computer systems _ but Iran has all along maintained that Stuxnet was only found on several laptops belonging to plant employees and didn't affect the facility's control systems.
Some computer experts believe Stuxnet was the work of Israel or the United States, two nations convinced that Iran wants to turn nuclear fuel into weapons-grade uranium.
The Rosatom agency said Monday that damaged elements were found in a cooling pump at the plant, raising the possibility that metal particles could get on the fuel assemblies.
Iranian Foreign Minister Ali Akbar Salehi told reporters in Geneva on Monday that the decision to remove the fuel was taken because of safety concerns.
"While in the process of the startup we make routine tests and repeat our tests," he said. "Because safety and reliability is our priority in the startup and running of a reactor, therefore we have come to an agreement with the Russians that if there is a case that needs revisiting of the equipment then we better do that in order to make sure that safety and reliability are met," he said.
The Bushehr plant was to go online this year, and it was not immediately clear how long the unloading, repair and reloading would take.
The inauguration of the facility has been delayed for years.
Iran said when it began inserting the fuel rods in October that the 1,000-megawatt light-water reactor would begin pumping electricity to Iranian cities by December. But it pushed back the timing to February, citing a "small leak" and other unspecified reasons.
The United States and some of its allies believe the Bushehr plant is part of a civil energy program that Iran is using as cover for a covert program to develop a nuclear weapons capability. Iran denies the accusation.
The Bushehr plant itself is not among the West's main worries because safeguards are in place to ensure that the spent fuel will be returned to Russia and cannot be diverted to weapons making.
The Bushehr project dates back to 1974, when Iran's U.S.-backed Shah Mohammed Reza Pahlavi contracted with the German company Siemens to build the reactor. The company withdrew from the project after the 1979 Islamic Revolution toppled the shah and brought hard-line clerics to power.
In 1992, Iran signed a $1 billion deal with Russia to complete the project and work began in 1995.
Under the contract, Bushehr was originally scheduled to come on stream in July 1999 but the startup has been delayed repeatedly by construction and supply glitches.
Associated Press writer Frank Jordans in Geneva contributed to this story.