"Russia has demonstrated more caution recently about anything to do with Iran's efforts to develop weapons of mass destruction," he told army radio.

Olmert, who was on hand to greet Putin on his arrival in Israel late Wednesday, refused to give any other details about the Russian position.

Questioned by AFP, a source in the office of Israeli Prime Minister Ariel Sharon implied Moscow was anxious not to sacrifice its own interests to Iranian nuclear ambition.

"The Russians realise the Iranians are hiding part of their nuclear projects from them, which risk endangering their strategic interests, but also some of their southern territory," the official said.

"Moscow has recently moved towards the European and American positions in trying to reign in the Iranians, but it is not enough," added the official on condition of anonymity.

"For months Sharon has insisted on the need to transfer the Iranian nuclear case to the UN Security Council in order to press sanctions against the Islamic republic should it refuse to halt its military nuclear programme," he said.

Tehran has consistently insisted that its atomic activities are purely civilian.

Russia is opposed to a military nuclear program for Iran and will cooperate with Tehran "solely in civil nuclear development," Putin said just days before flying into Israel.