JERUSALEM, May 18 (Dan Williams/Reuters) - Israeli Prime Minister Benjamin Netanyahu convened top advisers on Tuesday to assess an Iranian nuclear deal with Turkey and Brazil that may stall the new UN sanctions Israel seeks against Tehran, officials said.

The unscheduled inner cabinet meeting, accompanied by an announcement from Netanyahu's office that ministers were under orders to withhold public comment, reflected Israel's worries about the efficacy of foreign efforts to negotiate with Iran.

Israel, widely assumed to have its own atomic arsenal, has hinted at military strikes, as a last resort, to deny its most powerful foe the means to make a nuclear bomb. But it faces big tactical challenges as well as Western reluctance to see another regional war.

World powers voiced doubt over whether Iran's agreement on Monday to ship some low-enriched uranium to Turkey would be enough to address wider concerns about further fuel production.

Iran, which insists its nuclear program is peaceful, said the deal aimed to fend off a fourth round of UN Security Council sanctions.

Netanyahu has so far endorsed Security Council diplomacy, while urging US and European efforts to toughen up sanctions.

First word of the compromise bid by Brazil and Turkey, both of which are non-permanent members of the Security Council, drew a mixed response from Israeli officials who spoke to the media before being muzzled by Netanyahu.

Iran is equipping itself, intent on getting (nuclear) weapons. It is taking steps that are far from being for the sake of Iran's self-defense, as the president of Brazil would tell it, Deputy Defense Minister Matan Vilnai said. We are watching this, and making decisions accordingly, he told Israel's Army Radio. Trade and Industry Minister Binyamin Ben-Eliezer, a former defense chief, said Israel could only know with time if, with the new deal, Iran was continuing to toy with the whole world or was open to placing curbs on its domestic uranium enrichment.

Ben-Eliezer was cautiously upbeat about the intervention by Turkey. Ties with Ankara have been strained following its strong condemnation of Israel's offensive on the Gaza Strip in 2008 and its policies toward the Palestinians.

Turkey is certainly a regional superpower, Ben-Eliezer said on Israel Radio. Listen, 72 million people live there. And to say that they would be happy with their neighbor going nuclear? Certainly not. (Editing by Samia Nakhoul)