Then Russian president Vladimir Putin ordered the sabotage of Iran's nuclear programme in 2006, according to WikiLeaks documents published by Israeli daily Yediot Aharonot on Thursday.
The leaked documents, which were not immediately available on either the Yediot or Wikileaks websites, purportedly detail talks between the head of Israel's Atomic Energy Commission and then-US ambassador to Israel Richard Jones.
During a February 2006 meeting, Gideon Frank told Jones "at length about the results of his secret meetings with top figures in the Russian security establishment and intelligence community," Yediot reported.
Among the officials he met were then defence minister Sergei Ivanov, foreign minister Sergei Lavrov and the chairman of the Russian Atomic Energy Commission, Sergei Kiriyenko.
He told Jones Putin had personally ordered measures to delay progress at Iran's Bushehr nuclear plant. Under a 1995 deal, Russia agreed to complete the plant and provide the fuel, with Iran committing to return the spent fuel.
"Frank said that Kiriyenko had told him that he intended to delay the process of sending the nuclear rods to the reactor in Bushehr for an extended period of time and that he had no intention of supplying the reactor with 'fresh fuel' at the current stage," Yediot reported.
Kiriyenko told the Israelis "the Russians intended to explain the deliberate delay by means of 'technical problems,'" adding that "Putin had personally ordered that deliberate delay in delivery," the newspaper said.
Frank also said the Russians had told him "they had made changes to the hardware that they were supposed to send to the Bushehr reactor so as to slow down the Iranian nuclear program even further."
Russia, which has been a long-standing nuclear partner of Iran, voted in favour of UN sanctions against the Islamic republic last June.
Israel and much of the international community fear that Iran's nuclear programme masks a push to develop nuclear weapons. Tehran denies the charge, saying the programme is for civilian energy purposes only.