A British nurse who weighed 134kg has been refused New Zealand residency because of her morbid obesity, despite the need for skilled nursing staff.

But her body mass index of 55.2 was considered unacceptable by the immigration service who declined her application, despite nursing being on a long-term skill shortage list.

For a New Zealand European, a BMI score of 25 is considered overweight, 30 obese and 40 morbidly obese.

The woman, whose waist measured 131cm, wanted to emigrate with her crane driver husband and daughter, who has a degree, after holidaying in New Zealand in 2007.

Medical assessors said that the woman would probably cost the country $25,000 over four years in health treatment.

A medical assessor said that apart from her morbid obesity, she was an otherwise "well lady" and could be reconsidered for immigration if she reduced her BMI to under 40.

The appeal board said that the woman scored relatively highly in the skilled migrant category.