Patna, Feb 16 (IANS): Police have arrested a dozen persons for helping 254 students cheat in Class 12 exams. All the pupils have been expelled, official said.

"The students were expelled on charge of adopting unfair means," a Bihar School Examination Board official said.

The highest number of students caught cheating and expelled was over 30 in Nawada district on Thursday, the third day of the examinations.

More than 200 were expelled on Wednesday, second day of the examination, and 100 on Tuesday.

The authorities have decided to take tough measures to conduct cheating-free exams.

Thousands of officials, including teachers and policemen, have been deployed to hold free and fair exams, said the board chairman Anand Kishore.

The examination centres were being monitored by CCTV cameras.

To curb mass cheating, the authorities have decided to impose a fine on students found using unfair means and punish the guardians found helping their children cheat.

Parents, guardians or friends found helping students to cheat would be sent to jail.

More than 12 lakh students are appearing for Class 12 exams at 1,274 centres across the state.

Students caught cheating would be expelled for three years. Earlier, the board debarred them only for a year.