The Tertiary Education Union has recently highlighted nationwide problems with "ghostwritten essays".
A senior lecturer at Ara Institute of Canterbury said the problem tended to be more prevalent among international students, but had knowledge of instances involving domestic students.
"In some cases they've been not a hundred percent sure how to do an assignment," the lecturer said.
University of Canterbury deputy vice chancellor Professor Ian Wright said there "was no evidence to suggest" that cheating was a severe issue, or that any departments specifically had higher rates.
UC students had been reminded that "breaching academic integrity can lead to serious consequences, including exclusion from the university".
An anonymous Ara Institute of Canterbury student said an ex-classmate had offered to write on others' behalf, and that she was personally requested to do so.
"I have been asked for free [to ghostwrite]; just some really basic ones... I've had some students ask me 'can I have a copy of your assignment?'."
Professor Wright said curbing the issue of dishonest work would come down to education by "making sure students understand" that academic progression is self-driven.