Niuean is a Polynesian language spoken by about 8,000 people, the majority of whom live in New Zealand. There are also Niuean speakers in Niue, where almost the entire population of about 2,000 speak the language, the Cook Islands and Tonga. The closest relative of Niuean is Tongan, while Maori, Samoan, and Hawaiian are also quite close.
Niuean was first write by Christian missionaries in the mid 19th century using a spelling system influenced by Samoan.
source
wikipedia.org,
omniglot.com &
ethnologue.com