Lawyers for Tongan overstayers caught up in a visa scam want a written agreement from the Government that protects victims who go to the police.
Up to 2000 Tongans are estimated to have paid $290 for bogus residence visas, and lawyers say many are too scared to lay complaints.
Police in south Auckland say the fear of being deported is a barrier to their investigation into the scam.
They joined Immigration officials at a public meeting on Saturday to reassure victims they would not be deported during the inquiry and would have their cases reviewed afterwards.
Lawyers Amelia Schaaf, one of those who called the meeting, said a verbal assurance isn't enough.
Ms Schaaf said the lawyers want a meeting with Government representatives to draw up clear procedures for dealing with overstayers who report immigration scams.