The Independent Police Conduct Authority is investigating a complaint that police officers assaulted a 41-year-old Indian woman during an Immigration New Zealand visit to her home.
A female police officer allegedly bent the finger of Pooja Kapila, and another male officer prised her hand open and forced a thumb on to an ink pad to get her fingerprints for forms required to deport her family.
Police yesterday said they had already started their own investigation, but the independent investigation would establish whether the matter was handled appropriately.
Supporting medical documents from Bayfair Doctors said Mrs Kapila had minor bruising and swelling, decreased sensation in her fingers and "marked decreased range of movements" of her hand and wrist.
Mrs Kapila said the family had been in New Zealand for about 10 years, and intended "to stay here with my children" even if her husband was deported.
Mrs Kapila said: "My fingers were pulled back ... I asked them to stop. I was crying because they were hurting me, but they didn't stop."
The complaint, lodged by her immigration agent Tuariki Delamere, said the two officers went to Mrs Kapila's home in Te Puke with an immigration officer three days after arresting her husband, Satinder Kapila, on October 18.
Immigration needed Mrs Kapila to sign applications for travel to India for herself, 13-year-old daughter Simran and a New Zealand passport application for her 9-year-old son Abhay, a New Zealand citizen, so they could be sent to India with Mr Kapila.
"One of the officers tried to get her to sign but Pooja made her hand into a fist," the complaint said.
"On instruction from Neil Fellows, the INZ officer, the female police officer then grabbed Pooja's right hand index finger and bent it back until she started crying with the pain."
"The male police officer, a Maori, then grabbed her thumb and prised that open, causing further pain and suffering and forced the thumb on to an ink pad so that a thumb print could be made into the application forms."
A separate complaint has also been lodged with Immigration New Zealand over its officers' involvement in the alleged assault.
Mr Delamere described it as "the tactics of a police state mentality".
Police spokeswoman Annie Coughlan said the immigration officer was one the police officers had worked with on several occasions.
"Police were asked to obtain fingerprints. There has been an allegation made," she said.
"We are disappointed about the use of such emotive language and the nature of the claim.
"However, such allegations are taken extremely seriously."
