More than 5,000 people were detained in a campaign of “severe repression” following last year’s Iranian elections, according to an Amnesty International report.
The reports records “widespread abuses” and “suppressing freedom of expression to an unprecedented level”.
“Compelling evidence emerged that a number of detainees, both women and men, had been raped and otherwise tortured in detention,” the human rights watchdog said in the annual report released in London, echoing controversial allegations made by Karroubi.
The condemnation comes ahead of a UN Security Council vote on a draft resolution to impose sanctions on Iran over its suspected nuclear activites.
Iranian authorities reacted furiously to the charges, but were forced to admit abuses at south Tehran’s notorious Kahrizak detention centre, which was closed after at least three protesters died of injuries inflicted in custody.
President Mahmoud Ahmadinejad’s main rivals,including Mir Hossein Mousavi and Mehdi Karroubirivals, remain vocal in rejecting his government and its hardline “cult” following.
Terming the current Iranian year a “year of perseverance”, Mousavi, who as a former prime minister under revolutionary leader Ayatollah Ruhollah Khomeini, was once a pillar of the regime, issued his harshest criticism yet of the “tyrant” government on February 2.
“Stifling the media, filling the prisons and brutally killing people who peacefully demand their rights in the streets indicate that the roots of tyranny and dictatorship remain from the monarchist era… I don’t believe that the revolution achieved its goals,” he said on his website Kaleme.com.
Ahmadinejad’s main rivals, and eight other opposition groups are seeking to hold new anti-government demonstrations over the “fraudulent” official results.
Such criticism has stoked a furious war of words with the regime over who represents the true legacy of Khomeini’s revolutionary leadership.
Khamenei, who has openly defended Ahmadinejad, warned opposition leaders on Friday that former closeness to Khomeini was no guarantee of loyalty to his teachings.
The cleric recalled that some of Khomeini’s earliest supporters had betrayed the regime and been punished accordingly.
“Some came with the Imam from Paris and, after a while, due to treason, were hanged,” he said, referring to Khomeini’s return from exile in the French capital which triggered the revolution.
Iran’s hardline regime crushed public protests against Ahmadinejad’s controversial re-election last year, but 12 months on his rivals remain vocal in opposing his “cult” government.
Resorting to deadly violence and mass arrests, the authorities snuffed out the wave of huge street demonstrations that followed the announcement of the official results of the June 12 2009 vote.
But opposition leaders continue to challenge the regime’s claim to be the true followers of the Islamic revolution which overthrew the Western-backed shah in 1979 and advocate a change of leadership and direction.
Street protests against Ahmadinejad and chants of “Death to Dictator!” are no longer seen or heard but fresh clashes between pro- and anti-regime elements could erupt on the anniversary of the election on Saturday.
Bloody protests first broke out immediately after the hardline incumbent was declared the winner and intensified after he described his opponents as “dust and dirt” at a Tehran victory rally.
In the following days and weeks, running street battles between security forces and anti-Ahmadinejad protesters in what came to be known as the Green Movement erupted in the capital and other cities leaving dozens dead.
The political turbulence split the nation’s clerical elite, dragged all-powerful supreme leader Ayatollah Ali Khamenei into the crisis and left authorities grappling with bloodshed and international condemnation.
The intense cat and mouse chase between protesters and security forces lasted through the summer into the winter.
The regime reacted with an iron fist, rounding up politicians and journalists close to Mousavi and Karroubi and unleashing its feared Basij Islamic militia on anyone prepared to demonstrate in the streets.
Iran also sentenced 10 protesters to death and hanged seven people on security charges unrelated to the election but seen as a warning to opposition groups.
The sustained assault on regime opponents and the massive deployment of security forces at public events have kept protesters off the streets in recent months.
The turning point was the February 11 anniversary of the 1979 revolution, a cornerstone public event for the regime and one which the opposition had planned to hijack.
Hundreds of thousands of regime supporters backed by thousands of militiamen and security personnel spread across Tehran and quelled all attempts by the opposition to stage demonstrations of its own.