Lucknow, Oct 13 (IANS): The principal and three teachers of the SGPGI branch of Lucknow Public School here have been named in a police complaint for allegedly thrashing three students and locking them in a classroom, police said.

Based on the complaint filed by the father of one of the students at the Sanjay Gandhi Postgraduate Institute of Medical Sciences (SGPGI) police station here late Friday, a probe was launched into the case Saturday, a police official said.

Three students - Saurabh Kumar Pandey (Class 10), Shubhang (Class 11) and Ankit (Class 11) - complained that they were locked up in a classroom after the school staff alleged that they had leaked a mid-semester exam paper.

The principal and the three teachers grilled the students for more than four hours and when the trio refused to confess of any wrong-doing they were beaten up by sticks and canes, the complaint states.

Police sent the students for a medical check-up after they said they had concussions, blue marks and other injuries inflicted on them by the teachers.

Police said that tough action would be taken against the teachers if they were found guilty.

Despite repeated attempts by IANS, school authorities declined to comment on the issue.