The New Zealand Law Society says new powers for immigration officers to arrest and detain overstayers for deportation are a recipe for disaster and should be put on hold.
Immigration New Zealand says three people have been detained since the new powers came into force on Monday.
The Law Society says it has grave concerns the immigration officers are not properly trained and better safeguards are needed for overstayers.
Immigration committee convenor John McBride told Radio New Zealand's Morning Report programme on Wednesday that overstayers who have applied to have their visa restored could find themselves arrested and on a plane within four hours, with no explanation.
He said arrests and detention of overstayers should be left to the police, who are better trained and independent of the Immigration Service.
Auckland Tongan Advisory Council chairman Melino Maka sees the powers as a return to the era of dawn raids and says they will send overstayers deeper into hiding.
Immigration New Zealand general manager Peter Elms told Morning Report the power of detention is only for up to four hours and will typically be the time it takes to transport an overstayer to a police station. He said the change will free police for other work.
Mr Elms said immigration officers will not carry out dawn raids unless they know someone leaves for work before 7am.
The Chief Ombudsman, Beverley Wakem, is not worried about the new powers, but her office will watch closely how they are used.
Dame Beverley said what she has been told about the training for immigration officers gives her confidence that the opportunity for abuse will be limited.