In a press release yesterday the authority praised detectives for the way the inquiry was managed saying it was robust and thorough, and that all available offences were properly considered.
But New Zealand First MP Tracey Martin said the authority was hiding behind a secrecy provision and called for the release the full report, not just a press release.
"It's appalling that the Independent Police Conduct Authority has refused to produce a public report on police actions in a case in which girls were apparently deliberately intoxicated by young males and lewd photographs posted online," said Mrs Martin.
"It says the investigation by police was robust and thorough - if so, then the authority should reveal just how it was done. They could do this and protect the identity of those involved."
She said the authority should explain why no charges were laid and why the male students were only given a warning.