Social media posts helped Otago University figure out that 15 medical students had lied about how they spent six-week work placements in Eastern Europe.
The university has sanctioned the final-year students for spending most of their elective placement on holiday, instead of gaining experience of a foreign health system.
Its dean of medicine, Barry Taylor, said the Christchurch-based students were guilty of academic misconduct.
"Most of them have actually been there for a six-week period and there's obviously a week allowed for travel, so instead of five weeks the vast majority of them have only spent the one week in the centre where they were [supposed to be] and then they've produced a report suggesting that they were there for the full five weeks," he said.
Prof Taylor said the false reports were the most serious aspect of the case.
"They've written a report that is actually false and signing their name to a document that says 'this is what I did', when it is not. What they did is, in my book, quite serious misconduct and actually gives you real concerns about what they might do in the future," he said.
"This puts a stain against their future."
Prof Taylor said the students' behaviour would be considered when the university decides if they pass their final year, and it was possible they might have to make up for the time they had spent on holiday.
"They are also automatically being referred to our fitness to practice committee and that is likely to lead to their name being given to the Medical Council, who will then have that on their professional record," he said.
In addition, the students had to rewrite their reports about their placements and write an essay about professional practice.
The university began investigating in June after it received evidence the elective placements were being abused, Prof Taylor said.
He said some of the evidence against the students included social media posts.
Prof Taylor said he did not think the practice was widespread.
"It's a high-trust environment, I guess that's the issue. We trust these students that they will go and do what they've organised and what we've signed off on.
"I personally think it is a minority of students, and if it has been happening it's probably been ... building up over two or three years."
Prof Taylor would not identify the country the students had gone to. He said they had gone over the course of the year, not as a group.
The university said sixth-year medical students could use up to 12 weeks of their year for elective placements that could be spent on research, working in specialist areas of medicine, or working overseas.
The students were paid a stipend of $26,756 in their final year and the university had asked the 15 students to repay some of that money to the government.
Minister of Education Chris Hipkins said the university had taken an appropriately firm line against the students.
"This is a pretty serious deal. Those students have abused trust, they've acted in a way that's dishonest, that's not the sort of behaviour that you would want from people who are aspiring to enter into the medical profession," he said.
Hipkins said the government had been in touch with Otago and Auckland universities and the case appeared to be isolated.
Medical Students' Association president Fraser Jeffery said it had been supporting students that were under investigation and would work with the University of Otago on its review of elective placements.
Jeffery said the elective was a valuable component of the final year of medical school, allowing students to gain an insight into the health system of other countries.
"It's unfortunate that these students didn't take full advantage of this opportunity. The investigation has shown they made an error of judgment in not completing the full placement. They have all now taken responsibility for their actions, and I trust that they will be able to move on with their careers once this process is complete," he said.