NEW DELHI: A team of the CID arrived at the residence of former West Bengal chief minister Mamata Banerjee in Kolkata on Tuesday as part of its investigation into the alleged signature forgery case.Officials of the state investigating agency, accompanied by personnel from the Kalighat police station and a large contingent of women police personnel, arrived at the party's central office at 30B Harish Chatterjee Street around late afternoon.The CID's move comes days after the agency served notices seeking information related to the alleged forging of signatures of TMC legislators on a proposal submitted to the assembly speaker for recognition of the leader of opposition.According to CID officials present at the spot, the search was sought on the basis of a reply submitted by TMC national general secretary Abhishek Banerjee to an earlier notice issued by the agency, news agency PTI reported."In his response, Abhishek Banerjee stated that signatures of MLAs were collected at the party's central office at 30B Harish Chatterjee Street. Based on that statement, we have come here as part of the investigation," a CID officer said.Abhishek Banerjee, who is in New Delhi with Mamata Banerjee, has been summoned by the CID to appear before it by 5 pm on Tuesday in connection with the case.The investigating team initially faced resistance while trying to enter the premises, leading to a brief standoff with security personnel stationed at the complex.TMC leader and former MP Subhasish Chakraborty had earlier said the party would not allow any search operation in Abhishek Banerjee's absence."We have not allowed the CID to enter the premises in the absence of Abhishek Banerjee. Once he returns, the CID can search the house," Chakraborty told reporters.However, the situation changed later in the afternoon when the CID arrived with a larger police contingent and entered the premises despite what officials described as "mild resistance" from security personnel.Senior officers from Kalighat police station reached the spot and were seen arguing with members of the security staff attached to the Kolkata Police. The officers reportedly instructed them not to obstruct the search operation.Sources said the CID team subsequently entered the residence-cum-office complex and began its search and verification exercise.In a related development, another CID team visited Abhishek Banerjee's office on Camac Street as part of the ongoing investigation.The developments mark a fresh twist in the alleged forged-signature case, which has snowballed into the biggest internal crisis in the TMC's 28-year history.The controversy began after a proposal sent to the Speaker seeking recognition of senior TMC MLA Sovandeb Chattopadhyay as Leader of Opposition allegedly contained forged signatures of several legislators. The allegations led to the registration of an FIR and a CID probe.The rebellion traces its immediate origins to the dispute over the selection of the Leader of Opposition following the Assembly elections.The crisis deepened when 58 of the TMC's 80 MLAs defied the party leadership and backed expelled MLA Ritabrata Banerjee for the post instead of the party's official nominee, Sovandeb Chattopadhyay.In a dramatic turn of events last week, the rebel camp seized control of the legislature party, elected Ritabrata Banerjee as Leader of Opposition and secured recognition from the Assembly Speaker, triggering the first split in the TMC since its formation in 1998.The CID's simultaneous visits to the party's Kalighat headquarters and Abhishek Banerjee's office are being viewed as a significant escalation of the probe into the alleged forgery at the centre of the political turmoil engulfing the ruling party.