Siddiqui said people are "forced" to take BSP membership through coupons.
"In the name of membership, a lot of things happen. I can't even tell that to you," he said.
He also alleged that he gave the party several lakh rupees collected in the name of membership drive and there is no account of it.
Another former BSP stalwart, who defected to BJP last year, Swami Prasad Maurya claimed that booklet is a code word of BSP.
"When it comes to booklets, 'Kitab' is a code word of BSP. It can refer to Rs. one lakh or even one crore," Maurya said.
BSP has maintained that it generates funds through memberships and coupons.
"In BSP, booklets mean something else and membership is just an excuse. MP's, MLA's and candidates are forced to submit money from their constituency to the organisation," Maurya said.
It's claimed that anyone, who is above 18-year-old, can become a BSP member by purchasing membership coupon of Rs. 50.
Siddiqui, a general secretary who has been with the party since the time of its founder Kanshi Ram, was suspended from the BSP's primary membership on the charge of "taking money" from ticket seekers ahead of the February-March elections in Uttar Pradesh this year.
He claimed that although he had not taken any money from anybody, Mayawati kept on asking him to deposit the amount with the party. According to Siddqui, these 'booklets' are the reason behind his expulsion from the party.
At a media conference in Lucknow, Siddiqui claimed that Mayawati had demanded Rs 50 crore from him after the Assembly elections that ended in a crushing defeat for the former chief minister's party.
In one of the audio tapes released by Siddiqui, the voice purported to be that of Mayawati asks him to furnish details of membership books that had been distributed among BSP supporters.