Iran's nuclear moves are becoming harder for Israeli and U.S. intelligence to assess, making Teheran's suspected atomic weapons drive an even more urgent matter, Defence Minister Ehud Barak said on Thursday.
He was commenting a report in the newspaper Haaretz that said U.S. President Barack Obama had received a National Intelligence Estimate (NIE) saying Iran had made significant and surprising progress toward military nuclear capability.
"There probably really is such an American intelligence report -- I don't know if it is an NIE one -- making its way around senior offices (in Washington)," Barak told Israel Radio.
"As far as we know it brings the American assessment much closer to ours ... it makes the Iranian issue even more urgent and (shows it is) less clear and certain that we will know everything in time about their steady progress toward military nuclear capability."
Israel sees an atomic armed Iran as a threat to its existence and there is persistent speculation over whether it will launch a pre-emptive military strike against the Islamic republic's nuclear facilities.
Tehran denies it is seeking to build the bomb, saying it is enriching uranium only for peaceful purposes.
Israel, widely believed to have the Middle East's only nuclear arsenal, says little time remains before Iran achieves a "zone of immunity" in which Israeli bombs would be unable to penetrate deeply buried uranium enrichment facilities.
The United States has said it is determined to stop Iran gaining atomic weapons but has urged Israel not to launch a unilateral attack and instead to give more time for sanctions against Teheran to work.