The Central Board of Secondary Education on Wednesday instructed examination centres to ensure safe delivery of answer books to its headquarters a day after a lawyer complained to the CBSE of answer sheets of Class XII Chemistry exam being transported in the Delhi Metro. The board has asked the centres to make sure that such incident is not repeated. A commuter on the Blue Line, Tarun Narang, who happens to be a lawyer, had spotted an employee of Mata Kasturi Devi Senior Secondary Public School, Najafgarh, carrying a packet of Chemistry answer sheets on Tuesday. The lawyer was travelling from Dwarka Court Metro station to Janakpuri around 3 pm. Upon questioned by the lawyer on Metro the employee said that the examination superintendent had asked him to drop the answer sheets at the headquarters in Preet Vihar. Tarun wrote to the education board\u2019s examination controller asking for steps to be taken to prevent such incident as it compromised the security and violated the Board\u2019s provisions. Following the letter, the board has asked examination centres to maintain secrecy and security of the answer books in detailed guidelines issued on Wednesday. As per the guidelines, a school teacher from the examination centre has to take a private vehicle and drop the sheets at CBSE nodal centre. The lawyer had in his letter sought action against the centre superintendent and also demanded an inquiry into the matter, but was assured by the CBSE that no violation of the exam and answer sheets occurred. The education board, however, made it clear that the answer books were not leaked and the examination has not been violated by any means. A senior official of CBSE said that the board has directed the centres to personally ensure safety of the answer sheets and asked officials that incidents such as these should not be repeated. The school is yet to officially comment on the matter.