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Amy had hidden the fact she was transgender from Battle of the Babes because she was worried she would be disqualified, but confided in one of the organisers on Tuesday.
She was told that because she hadn't gone through gender reassignment surgery she couldn't compete.
"She was really keen for me until she knew I was transgender."
Amy went to the Human Rights Commission as well as Northland lawyer and member of TransAdvocates, Kelly Ellis. A number of her friends also sent emails and messages to the organisers complaining about her treatment.
By Wednesday a Facebook message apologised for the "misunderstanding", and said Amy would be allowed to compete.
Hours later, an addition was spotted in the rules section of the official website, stating "contestants must be born female". It sparked another round of heated exchanges before it was removed.
Battle of the Babes' New Zealand organiser Andrew Featherston said the website change was "unfortunate", and was mistakenly published after he had reviewed the decision to bar Amy from the contest.
Telling her she couldn't compete was simply "confusion" on their part as they did not know enough about transgender issues to make an informed decision, he said.
"It was the first time we've had to think about it.
"The event is a female model search, so when presented with that situation we weren't sure whether she was still eligible," Mr Featherstone said.
The teen model would be "treated exactly the same as the other contestants", he said.
"In fact I don't even want to make an issue out of it on the night. I just want to proceed with the night as normal; she's a contestant, simple as that."
The Battle of the Babes Auckland final will take place tomorrow night at the Empire Tavern.