Alarmed by the leak of confidential documents from ministry offices and departments located in Shastri Bhawan, the security staff posted at the building has been instructed to keep an eye on non-verified vehicles that enter or leave the building premises after 7 p m. The step has been taken to prevent incidents like the one that happened sometime back when some corporate lobbyists, in connivance with lower-level staff at Shastri Bhawan, were caught moving confidential documents outside the building in the darkness of the evening.