In a set of do's and don'ts for the civil services aspirants, the UPSC has also asked them not to bring any costly items inside the examination halls.
"Electronic gadgets like cellular/mobile phones, any other devices for communication, laptop, bluetooth device, and calculator are banned inside the examination hall.
"Any infringement of these instructions shall entail disciplinary action against the candidates concerned including debarment from future examinations/selection," the UPSC said.
The civil services preliminary examination 2017 is scheduled to be held on June 18.
Tens of thousands of students appear in this prestigious examination from across the country. About 4.59 lakh had taken the last year's civil services prelims.
Of these, 1,099 have been declared successful, the result of which was declared on May 31.