Three Edmonton public high school students were caught cheating on their Pure Math 30 diploma exams, an Alberta Education official said Friday.

"In addition to the immediate invalidation of their exam results, we are seeking more and additional punishment," spokeswoman Zoe Cooper said.

Cooper said the students were caught cheating by their teachers.

Alberta Education may recommend that the students be forced to wait for one school year before they can write another diploma exam, meaning their graduations would be delayed. The provincial ministry is also passing information to Edmonton police, but Cooper said police would become directly involved only if people who are not students were implicated.

The overwhelming majority of students did not cheat, she added. "Their exam marks will not be compromised in any way."

Earlier this week, Alberta Education started investigating rumours that somebody had a copy of the exam and was giving it or selling it to others.

The Pure Math 30 diploma examination, written by senior high school students across the province on Jan. 22, is worth about half the final marks that students get in the course.