An 0800 phone number has been set up by police investigating the Roast Busters claims.
Anyone who would like to speak to the enquiry team is encouraged to ring the freephone number, said Detective Inspector Karyn Malthus, the head of the so-called Operation Clover.
The number is 0800 OP CLOVER (0800 672 568) and can be dialled from any New Zealand phone, including cellphones, police said.
"I can assure anyone who contacts us that they will be treated with compassion and respect. On behalf of the NZ Police, I want to reiterate our absolute commitment to anyone who has been a victim of this group, or anyone else who has been the victim of a sexual assault," Ms Malthus said.
"My enquiry team are all staff who are trained in child protection and adult sexual assault, we're aware school and university exams are on at the moment and we'd encourage anyone to call us at a time that suits them.
Please call us and we can help support you through the process."
A video with a personal message from Ms Malthus about the 0800 number has also been released onto Youtube and the NZ Police website.
The video will also be distributed on various police Facebook pages, and police are encouraging the sharing of the link to the video.
A team of 10 core police staff are working on Operation Clover, with additional support available from within Waitemata, and the Counties Manukau and Auckland City Police districts. The multi-agency investigation also involves CYFS, ACC, the Ministry of Education, and various counselling services.
See the police video here: