Correctional Services spokesman Manelisi Wolela has denied allegations that student leader Mcebo Dla.
Classes were suspended yesterday at KwaMakhutha Comprehensive High School, south of Durban, after some pupils started behaving strangely.
School principal Mdu Ngidi said the trouble at the school started last week on Thursday when a female pupil began crying for no reason.
"We are puzzled by what is happening at the school," Ngidi said. "It all started with one pupil breaking down and bursting into tears.
"When asked why she was crying she explained she had attended her sibling's funeral the previous day and now needed prayers because she was seeing strange things.
"We asked one of our staff members to pray for her. She got better but then the pupils helping her also " became possessed".
Ngidi said he contacted church leaders to come and pray for the pupils at school because they were preparing for final year examinations.
"On Wednesday the pastors came back to pray for pupils and teachers again when we had another outbreak of crying and a screaming spell," Ngidi said.
"During the prayer some pupils kept on saying strange things -speaking in tongues.
"Some of them said they wanted to drink blood.
"We prayed from 7am until midday.
"After Wednesday's incident we decided to suspend classes and only allowed Grade 12 pupils to come in because they have started their exams."
Ngidi said strange things usually happened at the school when Grade 12 pupils were about to start their exams.
"Some pupils just don't write exams because they are too sick," he said.
"All we need is prayer to calm the situation. Some of our teachers are also affected by what seems to be demons."
He said he hoped the incident would not affect the school's pass rate.
"We usually get an 80percent pass and we were aiming to better that with a 100 percent this year."