Dilip Singh Judeo, who resigned as a Union minister following a cash-on-camera scam, was Saturday served with a fresh notice by CBI to appear before it, agency sources said.
A similar notice has been issued to Judeo's personal secretary Natwar Rateria, they said.
CBI had earlier said that it would question the duo before registering an FIR on the controversy.
Sources had said their questioning would help the agency in ascertaining whether to convert the preliminary enquiry into a regular case under the Prevention of Corruption Act or go for a further probe.
Rateria's questioning would be the most crucial as he would help the agency in identifying other persons who were in the hotel room when Judeo was allegedly being paid the bribe.