The University of Otago's Medical School has confirmed it is investigating reports of third-year medical students cheating in the practical component of their exams, after parts of an email from medical school dean Professor Barry Taylor to students were published by student magazine Critic Te Arohi.

The university is withholding the students' results until the investigation is complete.

Prof Taylor said in a statement this afternoon there had been "communication between some students regarding the content of examination stations", but he wanted to assure the public that candidates could not quickly learn the material to pass.

"Foreknowledge gives some advantage, but we think only a small advantage. These students still have three years to go in their training and in each year they are very carefully assessed in great depth."

The exams involved demonstrating a practical skill - such as taking a patient's history or examining someone presenting with headache symptoms.

The main issue was one of breaching professional boundaries, and it was an issue of "honesty and professional behaviour that we would not expect to see from people training to be doctors", Prof Taylor said.

Students alleged to have participated in the behaviour would be interviewed, but the consequences for them had yet to be determined.

"Staff and student leaders are extremely disappointed if the alleged behaviour has occurred. However, the public should be reassured that the standard of Otago Medical School graduate has not been compromised," he said.

Students quoted by Critic feared everyone would have to resit the exam and said there was a history of students passing on information to later groups.

"It's been like that forever," one said.

Students had been asked to help the university with its investigation, but one student said they were "definitely not gonna tell on someone".

The University of Otago declined to comment further or say how many students were affected.