Iran's parliament speaker Ali Larijani dismissed on Wednesday allegations by an opposition leader that male and female election protesters had been savagely raped in custody. 'The issue of detainees being sexually abused is a lie,' Larijani told parliament, the official IRNA news agency reported. 'Following an investigation of detainees in Kahrizak and Evin prisons, no cases of rape and sexual abuse were found,' he said, referring to the jails where most people arrested after the June presidential election were initially detained. Some protesters are still being held in the capital's notorious Evin prison, but authorities have closed Kahrizak jail south of Tehran after an order from supreme leader Ayatollah Ali Khamenei. Defeated presidential candidate Mehdi Karroubi claimed in a letter to powerful cleric Akbar Hashemi Rafsanjani that several male and female protesters had been raped in custody and called for an investigation. 'A number of detainees have said that some female detainees have been raped savagely. Young boys held in detention have also been savagely raped,' he said. About 4,000 opposition supporters were arrested over the unrest that swept Iran after President Mahmoud Ahmadinejad's disputed re-election, officials said. Most have been released, but around 200 remain behind bars. At least 110 have also been put on trial. 