Opposition leaders accuse the Iranian regime of Abu Ghraib-style torture of political detainees. Their followers spread dissident samizdat DVDs, use paintball guns to obliterate government posters, and attack government websites.

Despite nine weeks of savage repression since Iran’s hotly disputed presidential election, the opposition still refuses to accept defeat.

Mehdi Karoubi, one of the defeated presidential candidates, kept up the public pressure this week by claiming first that male and female detainees have been raped in Tehran’s Evin and Kahrizak prisons, and later that political prisoners were tortured to death.

“We observe that in an Islamic country some young people are beaten to death just for chanting slogans,” Mr Karoubi wrote on his Web site.

Other detainees “were forced to take off their clothes. Then they were made to go on their hands and knees and were ridden [by prison guards]. Or the prison authorities put them on top of each other while they were naked ... Do such treatments conform with Islam, which is a religion of mercy?” he asked.

Karoubi’s allegations, which are supported by Western human rights organizations, seemed designed to deepen rifts within the conservative establishment over the way detainees have been treated.

They certainly appeared to strike a nerve. The regime has denounced them as baseless, and demanded Karoubi produce proof.

Ayatollah Ahmad Khatami, a hardline cleric, used his sermon at Tehran’s Friday prayers yesterday to demand Mr Karoubi’s prosecution. He said his accusations were “full of libel, a total slander against the Islamic system” that helped Iran’s enemies.

Click here to read the full report from the London Times.