Rujira Banerjee was stopped at Kolkata airport on Monday when she was going to UAE.
Senior TMC leader Abhishek Banerjee's wife Rujira was grilled by the Enforcement Directorate (ED) on Thursday for nearly four hours in connection with the coal pilferage case, officials said.
The investigators had a three-page questionnaire for Rujira Banerjee, who reached the Enforcement Directorate office at CGO Complex around 12:40 pm.
"She (Rujira Banerjee) was asked questions about certain accounts in foreign banks. Her statements were recorded," an ED official told Press Trust of India.
Asked about Rujira Banerjee's questioning by the ED sleuths, West Bengal Chief Minister Mamata Banerjee declined to comment, stating that Rujira Banerjee would speak in case she felt there was any need.
"Please, (since) it's my family matter and I do not want to talk about it. Rujira is a mature girl. If needed she will talk about it," Ms Banerjee told reporters at the state secretariat.
Rujira Banerjee was stopped at the Kolkata airport on Monday when she attempted to board a flight to UAE with her two children. She was then served summons to appear before the agency at 11 am on June 8.
However, she reached the CGO Complex around 12:40 pm along with her lawyer. She left the ED office around 4.20 pm following her questioning.
Abhishek Banerjee, the Chief Minister's nephew has alleged the questioning was an attempt at "harassing" his family and was aimed at halting his mass outreach campaign ahead of the panchayat elections in the state.
Tight security arrangements were made around the CGO Complex to prevent any untoward incident, a senior police officer said.
Both CBI and the ED have earlier questioned Rujira Banerjee in the coal case.
The CBI is probing allegations of illegal-mining of coal from abandoned mines of Eastern Coalfields, estimated to be worth thousands of crores of rupees, officials said.
The Enforcement Directorate is probing the money trail related to the case.
The Trinamool Congress (TMC) alleged that the ED's action was part of a political vendetta by the BJP.
"Whenever Abhishek Banerjee was summoned, he cooperated. However, the way his family is being harassed is shameful. This is nothing but political vendetta by the BJP," TMC's state general secretary Kunal Ghosh said.
"The BJP is afraid of the TMC's 'Nabojowar' campaign ahead of the panchayat polls, and also wants to divert the attention from the train accident," he claimed.
The state BJP said the CBI and ED were independent agencies, and no political influence has been brought on them.
"The BJP has nothing to do with the investigation. The allegations are baseless, and if TMC has any complaints, let the party move court," state BJP president Sukanta Majumdar said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)