Trinamool Congress leader and West Bengal minister Aroop Biswas, who is under fire for the chaos at football great Lionel Messi's visit to Kolkata, has offered to resign to ensure an impartial investigation into the fiasco. According to sources, Biswas wrote to Mamata Banerjee, Chief Minister and Trinamool Congress chief, yesterday, offering to step down as the state's minister for Sports and Youth Affairs, Power and Non-Conventional Energy, and Housing. It is not yet known if the Chief Minister has decided on Biswas's offer to resign.