TEHRAN (Reuters) -- Opposition leader Mir Hossein Musavi has accused "establishment agents" of raping and abusing detainees imprisoned after Iran's June presidential vote and has urged the powerful clerics to do their duty and speak out.
"They [the authorities] asked those who were abused and raped in prisons, to present four witnesses [to prove their claim].... Those who committed the crimes were the establishment's agents," Musavi said in a letter to reformist leader Mehdi Karrubi, the reformist mowjcamp.com website reported.
"They were threatening detainees to keep silent...it is not possible to appease the suppressed people by using money and force," Musavi said.
In a forthright declaration that puts the Islamic republic's influential top clerics on the spot, Musavi demanded that they step in and pass judgment on a growing political scandal.
"It is the main duty of revolutionary clergy to reflect the realities, but some have closed their eyes and ignored this responsibility," Musavi's letter added.
His accusation lent support to Karrubi, who angered hard-liners for saying some post-election protesters were raped in jail. The authorities have rejected the accusations as "baseless."
"I praise your courage and hope the other clerics join and strengthen your efforts," Musavi's letter said.
Some hard-liners have called for Karrubi to be arrested or tried if he failed to prove the abuse accusations. Karrubi says he has evidence of mistreatment of detainees. On August 13, he said some of those arrested were killed under torture.
The June 12 poll and its turbulent aftermath have plunged Iran into its biggest turmoil since the 1979 Islamic Revolution, exposing deepening rifts within its ruling elite and also further straining relations with the West.
Iran arrested thousands of people after the election during its worst street unrest in three decades.
At least 200 people remain in jail, including senior moderate politicians, activists, lawyers, and journalists. Iran has this month staged three mass trials against detainees. A fourth trial will be held on August 19, official media reported.
Musavi and Karrubi, who came second and fourth respectively in the election, say it was rigged to secure hardline President Mahmud Ahmadinejad's reelection. Ahmadinejad and his allies deny it.
The hard-line president has until August 19 to present a cabinet to parliament for approval but may get a rough ride from the conservatives who dominate the assembly, as well as from his moderate foes who see his next government as illegitimate.
The losing candidates say 69 people were killed in unrest following the vote. The figure is more than double the official toll of 26.