Students are being encouraged to "snoop" on academics by texting a hotline if their teachers turn up late, the University and College Union has claimed.
Manchester Metropolitan Students' Union launched its "LATE" campaign after receiving a number of student complaints about lectures running late and being cancelled without warning.
The students' union then set up a phone line to test the scale of the problem.
"We've made it easy for you to tell us when your lectures start late or are cancelled without notice by using a simple text message," it says on its website. "All you have to do is send us a text with the word 'LATE', followed by the year and course you're studying."
Bold blue and yellow posters have been put up around the university, featuring the message: "If you're on time, why is your class LATE?"
But the UCU has condemned the campaign, suggesting that it is tantamount to asking students to spy on their lecturers.
A UCU spokesman said: "The relationship between lecturer and student is key to higher education, and schemes that encourage either to spy on the other, however well intentioned, undermine that bond.
"As the students' union accepts, lecturers are rarely late except with good reason. We believe students would be better off joining staff in campaigning against the increasingly high cost of their education, rather than acting unwittingly as an official level of university management by snooping on their teachers."
Nicola Lee, president of the students' union, admitted that reaction to the campaign had been "mixed".
She said the students' union simply wanted departments to inform students in advance if their lectures or seminars were cancelled.
"Of course, lectures sometimes have to be cancelled for legitimate reasons, but nearly 40 per cent of our students commute in.
"If they've had to pay for childcare, if they've had to go through rush-hour traffic to get here, only to find a notice pinned on the door when they arrive, it is not very fair," she said.
"We have had some feedback from students saying, 'My lecture has been cancelled without notice,' or, 'The learning has not been rearranged.'
"There was no way for us to test if this was common or whether cases were few and far between."
Ms Lee concluded: "This is not a witch-hunt: we are simply chasing up people's learning and making sure students are getting what they are entitled to."
This summer, students are set to adhere to their examination papers stickers that request feedback on their results.
As part of its "feedback amnesty" campaign, the National Union of Students will encourage students to put a sticker on the bottom of their scripts.
It reads: "Exam feedback helps me learn."
Aaron Porter, vice-president of the NUS, said the initial aim was to get more university departments to provide generic feedback, and in the longer term for tutors to talk through exam results with individual students or groups.
It follows a successful sticker campaign by Heriot-Watt University Students Association last year to demand more feedback.