The Tatas are understood to have written a 'general letter' to West Bengal's chief minister-in-waiting, Mamata Banerjee seeking her cooperation in matters of investment to be made by them in this state. The letter apparently has also said that the Tatas do not have any objection towards making fresh investments in West Bengal. The existence of such a letter and its receipt was confirmed to ET, by a very senior Trinamool Congress leader requesting anonymity.