A female environmentalist whose 10-year sentence was upheld by the Court of Appeals on February 18 says her interrogators tortured and threatened her with sexual assault.

The revelation was first made by BBC Persian which came into possession of letters and documents that Niloufar Bayani has managed to send out of the notorious Evin Prison where she has been held for two years now.

According to the report that the BBC has compiled Bayani was held incommunicado for eight months and her interrogators tortured her physically and psychologically for more than 1,200 hours, sometimes for twelve hours in one day.

Bayani has also revealed that her interrogators continually made sexual threats against her, showed her pictures of torture tools, made her listen to descriptions of others' tortures and execution for hours, and pretended that they were going to give her a paralyzing or lethal injection.

The revelation immediately led to a public outcry on social media by people living in Iran and abroad. The case is seen as one of the most brutal instances of prisoner mistreatment by the Islamic Republic.

Iran's Judiciary yesterday announced that the Court of Appeals has upheld the sentences of eight environmentalists, including Niloufar Bayani, for acting against national security and collaboration with the United States. Lawmakers and even the intelligence ministry have said there is no grounds for the arrest of the ecologists.

Bayani has revealed that she wrote to Supreme Leader Ali Khamenei and other high-ranking officials such as former Chief Justice Sadeq Larijani and described the abuse and torture but her torturers became even bolder.

Bayani's interrogators also showed her a photo of Kavous Seyed-Emami, the head of the environmental institute that she worked for. Seyed-Emami's body was found in his prison cell two days after his arrest and officials claimed he had committed suicide.