ANALYSIS - Iran vote stuns voices for reform, opening to West

By Alistair Lyon, Special Correspondent

BEIRUT (Reuters) - Mahmoud Ahmadinejad's disputed election win has frustrated reform-minded Iranians and dismayed outsiders who had hoped Iran might "unclench its fist" under a new leader and engage with U.S. President Barack Obama.

Israelis may see a silver lining in the result of Friday's presidential vote: Ahmadinejad's fiery rhetoric is their best weapon in convincing the world to halt Iran's nuclear ambitions.

But the Iranians who voted for moderate candidate Mirhossein Mousavi feel betrayed by what they see as the blatant rigging of a poll that has denied them even the limited choice on offer under the Islamic Republic's complex system of clerical rule.

"No one even imagined this much vote rigging, before the eyes of the world, by a government which says it is committed to religious justice," Mousavi complained. "(This) will jeopardise the pillars of the Islamic Republic and establish tyranny".

Supreme Leader Ayatollah Ali Khamenei endorsed the result and told all Iranians to avoid "provocative behaviour" and rally behind Ahmadinejad, who called the election "free and healthy".

The authorities have shown a firm hand against dissent since official results on Sunday gave Ahmadinejad nearly 63 percent of the vote and only 34 percent for Mousavi, belying the enthusiasm he had fired up among reformers and moderate conservatives.

Security forces did not fire on the thousands of pro-Mousavi protesters who took to the streets of Tehran on Saturday, but the televised images of uniformed men on motorcycles flailing their batons sent a clear signal, at least to the outside world.

The anti-Ahmadinejad camp was "taken by surprise and is scrambling for a plan", according to Trita Parsi, director of the Washington-based National Iranian American Council.