Eleven Alberta students are being punished for cheating on a math diploma exam earlier this year, provincial education officials announced Friday.

The source of the leaked test was determined to be a student who wrote the January Pure Math 30 exam in another country and was supervised by a family member, not a teacher.

"They would have had access to that examination a couple of days ahead of the actual writing and then they scanned it and sent it via email to their friends here," said John Rymer, the executive director of learner assessment with Alberta Education.

Rymer said officials were alerted when a student inadvertently blew the whistle on the whole scheme.

"The day before the examination the student in question went to the teacher and said 'How would I solve this particular problem? I'm having trouble understanding this,'" Rymer told CBC News. 

"The next day when the exam occurred, when the teacher saw the question, it twigged immediately that obviously a student must have seen that question."

Most of the students are from Edmonton schools. One is from Calgary. They will not be able to write the exam until January, which means some of them won't graduate in June. That may force them to postpone plans for college or university.

About 200 students were interviewed during the investigation.

Officials are now tightening the rules on how students write Alberta diploma exams in other countries, Rymer said.