Kolkata: Trinamool chief Mamata BanerjeeHis residence in Kolkata’s Kalighat and his office in Nabanna were placed under an unprecedented security lockdown on Monday, even as Bengal Chief Secretary Dushyant Nariyala directed all department heads to ensure that no official document is removed, damaged or copied without permission.Much before the final results of the assembly elections were declared, central paramilitary forces had rang the bell in Nabanna and stepped up surveillance outside the CM’s Kalighat residence as well as his house. Trinamool Congress National General Secretary Abhishek Banerjee, till Monday afternoon.The deployment comes amid celebrations by BJP supporters in parts of Kalighat and sporadic reports of tension in the state as trends show that the Trinamool Congress is facing defeat.The Chief Secretary’s order said, “All departmental secretaries and heads of offices are requested to ensure that no important paper or any file is removed/damaged or otherwise taken out of the offices. No unauthorized copying/scanning will be allowed. Proper account of all files/important papers/communications will be maintained. Heads of Departments and departmental secretaries will personally ensure that this is followed in letter and spirit.”Rapid response teams were deployed at the head offices of key government departments.The Election Commission said that these steps are purely precautionary.