"The issue is being investigated by the Central Bureau of Investigation (CBI) and it should not prolong its probe in the case and show its report to the nation as soon as possible," she said.
"Unless an investigation report (proves his guilt), it will be unfair to seek Bansal's resignation," Mayawati told reporters outside Parliament House. "Let the investigation report come. That will make the situation clear and a decision can be taken then," she added.
Bansal's nephew Vijay Singla was arrested last week by the CBI for allegedly accepting a bribe of Rs.90 lakh. The bribe was paid to him by two people for getting a senior railway officer, Mahesh Kumar, appointed as a member of the powerful Railway Board.
Bansal had issued a statement distancing himself from the incident involving his nephew.