Sources said the TMC leader is being interrogated for more than two hours as part of the ongoing probe into allegations that signatures of party legislators were forged on a letter submitted to the Speaker of the West Bengal Assembly.

The development follows a Calcutta High Court order directing Banerjee to appear before the CID at 6 pm on Thursday.

The court also granted him interim protection from coercive action for three weeks, subject to his cooperation with the investigation.

CID questioned Abhishek Banerjee after High Court directed appearance in signature forgery case.TMC national general secretary Abhishek Banerjee reaches CID headquarters at Bhavani Bhawan in Kolkata to join probe. Photo: IBNS

The order ensured that the state investigative agency could continue its inquiry while preventing any immediate punitive measures against the TMC leader.

Banerjee had earlier skipped three summons issued by the CID, citing health-related concerns.

He had sought an additional 15 days to respond to the agency's notices.

The CID investigation stems from a complaint lodged by TMC MLAs Ritabarta Banerjee and Sandipan Saha, who alleged that their signatures were forged on a letter nominating senior party leader Sovandeb Chattopadhyay as the Leader of Opposition in the West Bengal Assembly.

The disputed letter was submitted to Assembly Speaker Biman Banerjee on May 20, triggering a political controversy within the party and prompting a formal investigation.

Following the complaint, an FIR was registered, leading the CID to launch a probe into the circumstances surrounding the preparation and submission of the nomination letter.

Investigators are examining how the signatures appeared on the document and whether due procedures were followed before it was submitted to the Speaker.

As part of the investigation, the CID issued three notices to Abhishek Banerjee because he had signed the letter at the centre of the controversy.

The agency sought to record his statement and gather information regarding the preparation of the document and the process through which it was submitted to the Assembly authorities.

After failing to secure his appearance through earlier summons, the CID moved forward with its inquiry following the High Court's intervention.

TMC challenges CID search ops

The questioning of Banerjee comes a day after the Trinamool Congress approached the Calcutta High Court, challenging a CID search operation at the party office located adjacent to former Chief Minister Mamata Banerjee's residence in Kolkata's Kalighat area.

On June 9, CID officers visited the party office as part of the signature forgery investigation.

The TMC has questioned the legality of the search and sought judicial scrutiny of the operation conducted by the state investigative agency.