Central Bureau of Investigation (CBI) Special Judge Swarna Kanta Sharma started recording of the statement of Bansal, who was testifying as CBI witness in the case against his nephew Vijay Singla.
Bansal failed to appear before the court Sep 16 due to illness and the court on that day directed him to appear before it Sep 22.
Last week, the court began trial in the case against Singla and nine other accused.
The court had framed charges of criminal conspiracy under the Prevention of Corruption Act against all 10 accused in March.
The other accused in the “cash-for-post” case are suspended Railway Board member Mahesh Kumar, middlemen Sandeep Goyal, Samir Sandhir, Sushil Daga, Ajay Garg, Rahul Yadav, businessman Manjunath and his aides M.V. Murli Krishan and Venugopal.
The CBI had filed a list of 90 prosecution witnesses along with the charge sheet and named Bansal as a witness in the case.
Bansal resigned as railway minister after the case came to light last year.