A New Plymouth woman says she has lost her mana after a surgeon threw her son's amputated finger in the rubbish, despite having signed release forms to take it home.

Donna Moke said her son Kereopa, 19, severely damaged his right index finger last Monday while trying to clear grass from a lawnmower, the Taranaki Daily News reported.

He was rushed to hospital, where he was operated on. Both signed a release form before surgery, requesting the return of his amputated finger so it could be blessed and buried alongside Mrs Moke's grave.

The doctor who did the surgery did not read his patient's notes and threw away the finger. He has since apologised.

To Maori the body is tapu and body parts must be returned to the family so they could be buried appropriately.

Taranaki DHB in-patient services manager Lee McManus said the hospital had made a mistake and apologised to the family.

Mrs Moke had also lost several of her fingers in a lawnmower accident when she was 12.