Image caption The students were taking an undergraduate course in politics

Harvard University has imposed academic sanctions on dozens of students for cheating in a final exam, a dean said in an email to students.

"More than half" of 125 students under investigation were asked to leave for a period of time; others face probation.

An inquiry began when a tutor noticed identical answers to a take-home exam for an undergraduate politics course.

The review expanded to include nearly half the 279 students enrolled in the course, the Harvard Crimson said.

Correspondents say there have been complaints that exam rules for the Introduction to Congress class were unclear, and over the university's handling of the investigation.

'Communal reflection'

In an email to members of the university, Faculty of Arts and Sciences Dean Michael Smith said the cases had now been resolved.

"Somewhat more than half" of the cases resulted in a request to withdraw, he said.

Of the remaining cases, about half the students were placed on disciplinary probation and the rest were exonerated.

Some of those ensnared in the scandal were members of Harvard sports teams.

Two basketball co-captains have been dropped from the team, while earlier reports in the university newspaper suggested football, baseball and ice hockey players could also have been involved.

The dean added that an internal committee would put forward recommendations on how to promote honesty within the institution.

"This is a time for communal reflection and action," Mr Smith said. "We are responsible for creating the community in which our students study and we all thrive as scholars."