New Delhi, June 10 -- The Mamata Banerjee-led Trinamool Congress (TMC) camp on Tuesday hit back at the party's rebel Lok Sabha MPs, alleging that they lack "political morality and ethics" and termed them opportunists for trying to engineer a split. Meanwhile, suspense continued over the rebels' strength as there is no clarity on which TMC MPs have joined the other group and officials in Lok Sabha are unsure what is the status of the letter that the rebels have claimed to have submitted. On Monday, TMC MP Kakoli Ghosh Dastidar announced that they had given a letter from 20 MPs to Speaker Om Birla for a separate sitting arrangement in the House. In a press conference, TMC MPs Kalyan Banerjee and Kirti Azad even challenged the rebel MPs to make public the so-called letter of support. "They lack political morality. If they are so upset, they should have resigned and fought fresh election. Why is it that they never raised these issues in the last 15 years but now, when the party has lost, they decided to form a bloc," said Kalyan Banerjee. Banerjee also argued that the law only permits merger with other parties but the rebel MPs can't form a ginger group. Ghosh Dastidar, the face of the rebels, rejected the charges of opportunism and said, "I was with Mamata since 1984. I lost many elections but I never left the party when TMC was not in power," she told media. Banerjee also said that the BJP will not take any rebel MPs. Questioning the authenticity of the letter, Banerjee said such an important document has not been placed in the public domain. "If you are so honest, why don't you make it public?" he asked....