A follower, Hans Raj Chauhan, claimed that he, along with several other saints of the Dera, was castrated inside the ashram on the pretext of attainment of union with God.
He alleged that around 400-500 Sadhus were brainwashed by the Dera chief and told castration was a way of coming closer to God.
"Before the operation, Baba used to give SadHus some 'black tablets' in morning to sedate them. After in-taking drug, Sadhus would gradually lose the power of rational thinking," Hansraj told ABP News.
"With the drug, Baba would make them incapable of taking right decisions. Thus, he forced them to undergo this painful operation," he added.
Hansraj said most of Dera chief's followers were between 14 to 17-year-old. He said Ram Rahim also used to indulge in blackmailing during his 'satsang'.
A special CBI judge will pronounce the sentence against Ram Rahim, convicted of raping his two women followers, in a Rohtak jail on Monday.
The punishment can be a jail term not less than seven years but may even extend to life imprisonment.
After his conviction, his triggered widespread violence and arson in Haryana where 38 people were killed and over 250 injured after which curfew was imposed at several places in the state.