The CBI has summoned former Kolkata Mayor Sovan Chatterjee, who recently joined the BJP, in connection with the Narada sting case, sources said on Wednesday.
The investigating agency has also summoned Trinamool Congress MP Aparupa Poddar, they said.
Chatterjee has been asked to appear before the Central Bureau of Investigation (CBI) on Saturday and Poddar in the first week of September, the sources in the probe agency said.
In Delhi, the CBI earlier in the day questioned Trinamool Congress' Rajya Sabha MP K D Singh in connection with the case in which some persons resembling party leaders were seen accepting money, officials said.
The agency has also called Mathew Samuels, the editor of Narada news, who had provided the recordings purportedly showing alleged payments received by politicians and senior bureaucrats of West Bengal government.
In the sting operation, which was claimed to have been carried out in 2014, some persons resembling senior TMC leaders are seen accepting money from the representatives of a fictitious company in return for favours.
The CBI had booked 12 top TMC leaders, including MPs and West Bengal ministers, and an IPS officer in connection with the case.
An FIR was lodged for alleged criminal conspiracy under the provisions of the Prevention of Corruption Act dealing with bribery and criminal misconduct.