Cambridge, Massachusetts - Harvard University is investigating whether dozens of students cheated on an exam last spring.

Officials at the Ivy League school said they discovered students may have shared answers or plagiarized on a final take-home exam. They declined to release the name of the class, the students' names or the exact number being investigated, citing privacy laws.

The class had a minimum of 250 students, and possible cheating was discovered in roughly half the exams, university officials said Thursday.

“These allegations, if proven, represent totally unacceptable behavior that betrays the trust upon which intellectual inquiry at Harvard depends,” President Drew Faust said.

A Harvard spokesman said he knows of no incidents in recent memory of possible cheating at the university on this scale.

Teresa Fishman of the International Center for Academic Integrity at Clemson University said it is not surprising that Harvard isn't immune to possible cheating. She said 20 years of data shows that a quarter to a third of students across all levels of collegiate education admit cheating on tests.

Each student whose work is in question has been called to appear before a subcommittee of the Harvard College Administrative Board, which reviews issues of academic integrity, said Jay M. Harris, dean of undergraduate education. He emphasized that none of the allegations has been proven and said there's no evidence of widespread cheating at Harvard.

“Looking at the students we have and the work that they do, I would be loathe to say this is something that represents Harvard students generally,” Harris said.

A teaching assistant noticed some possible problems on the tests, including evidence that students collaborated on answers or used the same long, identical strings of words. The exam had clear instructions that no collaboration was allowed, Harris said.

The assistant notified the professor, who referred the case in May to the administrative board.

Depending on the offense, the punishments range from an admonition, a sort of warning for a first offense, to being forced to withdraw from Harvard for a year.

There's no timeline for when the investigation will be finished, Harris said. - Sapa-AP