New Delhi: Mamata Banerjee-led Trinamool Congress (TMC) claimed that it was unable to respond to a meeting request from Lok Sabha Speaker Om Birla as party leader Abhishek Banerjee was being questioned by CID in Kolkata at the time.According to TMC sources, Banerjee received an email from the Speaker's Office around 2 pm asking him to meet Birla at 4 pm on Monday. Shortly afterwards, the Speaker's Office also informed party MP Kirti Azad about the communication.Also Read: LS Speaker to decide on TMC rebel MPs after hearing both sides; meeting with Mamata Banerjee's factionAzad conveyed that Banerjee was cooperating with CID investigation in Kolkata and was therefore unable to attend the meeting at such a short notice. He later met Birla to explain the situation, sources said.The development comes amid a major split in TMC, with around 20 MPs announcing their decision to merge with little-known Nationalist Citizens Party of India and seeking recognition as the "real TMC".Sources in Parliament said the Speaker's office will hear both the defecting MPs and the Mamata Banerjee-led faction before taking a decision on the breakaway group's demand for separate recognition in the Lok Sabha. The Speaker is also expected to seek legal advice before deciding on the rebels' request, with any decision likely before the monsoon session of Parliament, scheduled to begin in July.Constitutional experts have questioned the validity of the rebels' move. Former Lok Sabha secretary general PDT Achary said Paragraph 4 of the Tenth Schedule permits the merger of one political party with another, but does not allow MPs or MLAs to independently engineer such a merger without the parent party's approval.A former Election Commission official described the proposed merger as an "innovation" with no clear basis in either the anti-defection law or the Representation of the People Act.Also Read: From Rs 75 in cash to the heart of a TMC revolt: The unlikely political journey of NCPIThe crisis escalated on Sunday when the rebel MPs met Birla and sought separate seating arrangements in the Lok Sabha. Rebel MP Kakoli Ghosh Dastidar said 20 TMC MPs had signed a representation to the Speaker, claiming support from two-thirds of the party's parliamentary strength."We will merge with the Nationalist Citizens Party and support NDA," she said.