Chennai: An 18-year-old candidate was caught using a mobile phone to cheat during the National Defence Academy (NDA) and Naval Academy examination in Chennai on Sunday, police said.

The exam, conducted by the Union Public Service Commission (UPSC) for filling 406 vacancies across the Army, Navy and Air Force, was held at several centres nationwide.

At a private school in Pulianthope here, an invigilator noticed that one of the candidates did not return to the hall even after more than 10 minutes of seeking permission to go to the toilet.

On inspection, the invigilator found the youth searching for answers on his mobile phone, police said.

The candidate, identified as Sheikh Omar Riaz of Perungudi, had allegedly concealed the device in his undergarments to sneak it into the exam hall. He reportedly tore pages from the question paper and used them in the toilet to search for answers online, they added.

Following a complaint from the school principal, police arrested the youth and are questioning him.