JERUSALEM, Dec 1 (Dan Williams/Reuters) - Israel's lobbying to get better American weaponry than U.S.-aligned Arab powers has been complicated by their shared hostility toward Iran, leaked diplomatic cables show.

Wikileaks disclosures from July 2009 document Israeli and U.S. defence delegates debating the merits of arming Saudi Arabia and other Sunni Arab states given doubts over whether Iran can be denied the means for developing nuclear weaponry. Hearing the Israelis' objections to the planned sale of F-15 fighters and missiles to the Saudis, State Department official Andrew Shapiro argues for a commonality of interests with the Gulf States, which also view Iran as the preeminent threat.

We should take advantage of this commonality, he says.

Shapiro's line appears supported elsewhere in the Wikileaks trove, which includes an account of Saudi Arabia urging the United States to attack Iran preemptively.

One Arab leader echoes Israeli Prime Minister Benjamin Netanyahu by likening Iranian President Mahmoud Ahmadinejad to Hitler. Another voices empathy for Israel in considering offensive military options against its arch-foe.

Yet Netanyahu is quoted as warning that should Iran get the bomb despite U.S.-led efforts to curb its uranium enrichment, Arab powers could shift loyalties from Washington to Tehran.

This spells a quandary for the Israeli envoys who have long handled negotiations on both securing Israel's Qualitative Military Edge with the most advanced U.S.-supplied arms, and ensuring that the Arabs -- some of them old foes -- get less.

According to the U.S. embassy cable from July 2009, Israel understands U.S. policy intentions to arm moderate Arab states in the region to counter the Iranian threat, and prefers such sales originate from the United States instead of other countries like Russia or China.

But Pinchas Buchris, a top Israeli defence official at the time, is described as having stated bluntly that it was not clear to him where U.S. policy was heading with regard to Iran.

Senior Israeli diplomat Alon Bar adds: A perceived closure in the capability gap between Israel and Arab states, coupled with a nuclear-armed Iran, could compel moderate Arab states to reassess the notion that Israel was a fixture in the region.

The document quotes Shapiro as reiterating the Obama administration's determination to deny Iran access to nuclear weapons, and agree(ing) that assistance to Gulf states should not diminish Israel's QME.

But Shapiro declines an Israeli request to review the U.S. report on planned Middle East arms sales before its submission to Congress, as it contained secret intelligence assessments.

The Obama administration announced last month it would go ahead with the $60 billion deal with Saudi Arabia. A Pentagon official, Alexander Vershbow, told reporters at the time: Israel does not object to this sale. (Editing by Samia Nakhoul)