The TMC on Thursday accused the BJP-led Centre of engaging in "political witch-hunt" as Enforcement Directorate (ED) interrogated party MP Abhishek Banerjee's wife Rujira Narula Banerjee in connection with a coal pilferage scam.

The party warned of protests if "harassment by central agencies" doesn't stop.

ED on Thursday quizzed Narula Banerjee at its city office in connection with its probe into the multi-crore rupees worth of coal scam, an official said.

She visited the agency's CGO complex office around 11 am, with her child in arms.

"The CBI and ED have been acting as agents of the BJP and harassing political opponents. The way Abhishek Banerjee and his wife are being harassed without any reason is unacceptable. This has to stop, or we won't sit idle. We will protest against it," TMC MP Santanu Sen said.

"This political witch-hunt by the Centre is shameful," he said.

TMC state general secretary Kunal Ghosh claimed that "cheap tactics" are being employed by the BJP to intimidate the TMC, which is one of the prime contenders in the elections.

Polling to four Tripura Assembly seats -- Agartala, Town, Bardowali, Surma and Jubarajnagar -- is underway in 221 booths since 7 am, and it will continue till 5 pm.

The state BJP leadership, however, denied the allegations as baseless and said ED is an independent agency devoid of any political influence.

"The BJP has nothing to do with the CBI investigation. The allegations are baseless. If they have any complaints, they can always move to the court. They had earlier also moved the court on this issue," state BJP president Sukanta Majumdar said.