Debris outside a student flat on Cumberland St, Dunedin. An initiation was held at the flats.

University of Otago's campus watch were called to Dunedin's student quarter after what appears to have been a disturbing flat initiation.

Hundreds of students filled the backyard of the flat, near the corner of Cumberland and Dundas streets, and cheered the antics.

Videos and pictures shared over Snapchat showed young people stripped to their underwear with the middle of their heads shaved and sculling drinks until they vomited.

HAMISH McNEILLY/STUFF A flat on Cumberland St, Dunedin, where an initiation was held on Thursday night. Videos and pictures shared over Snapchat showed young people stripped to their underwear with the middle of their heads shaved and sculling drinks until they vomited. (File photo)

One person who was at the Thursday party said one student lay on the ground as another crouched over him and urinated on his face.

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One video showed green substance from a wheelie bin being poured over a young man. The witness said partygoers were vomiting into wheelie bins.

Stuff has chosen not to publish the videos. The behaviour is part of "flat initiations", where departing tenants make the incoming leaseholders complete tasks.

A person who knew those taking part in the initiations said: "I was watching it and it was all just drinking beers and stuff."

Students at the flats, which back-on to where a balcony collapsed in 2016, were outside cleaning up glass and other debris on Friday morning.

A group of young men declined to comment when approached. "Just respect our privacy," one said.

The Invercargill-based landlord of the rear property said the flat complex had not yet been tenanted for next year, and they were not aware of any large scale parties.

A landlord of a neighbouring Cumberland St flat of nine young men said he had received no complaints from neighbouring businesses. His flat was leased earlier in the year.

The landlord, who declined to be named, said the partygoers may have been tenants from a nearby Castle St complex.

A spokeswoman said the University of Otago was aware of an event involving young people in Cumberland St.

The university's campus watch were called to the area after other university staff expressed concerns, she said.

"These concerns will be referred to the university proctor," she said.

"Students who may be involved need to be aware of the student code of conduct and serious consequences, including possible exclusion from university, of potentially harmful behaviour resulting from excessive alcohol consumption."

The code of conduct says organising initiations requiring drinking alcohol or drug use are "strictly forbidden". "The statement by any student that they willingly participated will not excuse the organisers of responsibility," it says.

University of Otago student president Hugh Baird had not heard about Thursday's initiation.

He said flat initiations were usually good-natured fun, but there was a line. Urinating or pouring vomit on someone was "a step too far".

Initiations he had been to involved drinking games and dress ups. Head shaving was "somewhat standard" – "hair grows back".

He said the flats in that area were in high demand. This time of year was common for a lease to change hands to groups moving out of halls.