Israeli premier Benjamin Netanyahu has sent an aide to meet Rabbi Ovadia Yosef, spiritual leader of ultra-orthodox party Shas, to win his backing for an attack on Iran, Israeli media said on Tuesday.

Yaakov Amidror, head of the National Security Council, visited Yosef, whose party is a member of Netanyahu's ruling coalition, at his home in Jerusalem on Friday to discuss the issue, Israeli media reports said.

A senior Israeli official, speaking on condition of anonymity, confirmed news of the visit to AFP, but did not give details on the discussions.

Thus far, Yosef has ordered Shas ministers to oppose any Israeli attack on Iran's nuclear facilities that is not coordinated with the United States.

Israeli commentators have said that Netanyahu and Defence Minister Ehud Barak do not have a majority in the country's cabinet or the security cabinet to carry out an offensive against Iran, hence the importance of Shas.

Army radio reported that, since the visit, Yosef has become less determined in his opposition to an Israeli attack.

It cited extracts from a religious commentary made on Saturday night in which Yosef likened Iranian leaders to Amman, a Persian enemy of Israel in Biblical times.

"We are all in danger," Yosef was quoted as saying. "We cannot rely on anyone except our father who is in heaven."

Israel believes the Islamic republic is trying to develop a military nuclear capability under the guise of its civilian programme which it says would pose an existential threat to the Jewish state.

Iran denies these accusations.