* Videos online show large crowd at reformist's funeral
* Chanting for release of Green movement leaders
* A week before tightly controlled presidential election
DUBAI (Reuters) - A funeral for a dissident Iranian cleric turned into a rare anti-government protest, videos posted online showed, with thousands of mourners chanting for the release of detained opposition leaders.
Little more than a week before a presidential election at which reformists have been barred or sidelined, the protest appeared to be of a scale unseen in Iran for at least two years when open dissent was crushed by the authorities.
Iranians will vote on June 14 for a successor to President Mahmoud Ahmadinejad, whose re-election four years ago provoked huge protests by reformists who said the result was rigged.
The state has always denied vote rigging and says the unrest was fomented by Iran's foreign enemies.
Reuters could not independently verify the authenticity of the videos, which show a broad boulevard packed with people following a coffin held aloft by mourners.
"The funeral service for Ayatollah (Jalaleddin) Taheri in the city of Isfahan was accompanied by slogans in support of detained leaders of the Green (reformist) movement," the opposition website Kaleme said.
Kaleme said Taheri, a senior cleric, was a well known reformist and had criticized Ahmadinejad's re-election as illegitimate.
It is not the first time a funeral has developed into a political protest. In December 2009, vast crowds attended the burial of Grand Ayatollah Hossein Ali Montazeri, considered a spiritual leader by the Green movement protesting Ahmadinejad's re-election.
The movement's two leaders, Mirhossein Mousavi and Mehdi Karoubi, were put under house arrest in February 2011 after they called for demonstrations in support of the Arab spring protests - seen by authorities as a attempt to rekindle protests that by then had been stamped out.
Several political hopefuls were barred by a state body and Iranians will have to choose between eight carefully vetted candidates in a field dominated by hardliners close to Supreme Leader Ayatollah Ali Khamenei.
(Editing by Robin Pomeroy)