The North and South Islands are now also officially known as Te Ika-a-Maui and Te Waipounamu, the Government has announced.

Land Information Minister Maurice Williamson has this afternoon also formalised the names North and South which previously had no formal standing.

The alternative names were confirmed following a recommendation from the New Zealand Geographic Board that people be given a choice about whether to use the English or Maori names for the islands.

Te Ika a Maui meant ''the fish of Maui'' and Te Waipounamu ''the waters of greenstone''.

The Maori names were recorded in early Government maps of New Zealand but that ceased in the 1950s and had "historic and cultural significance", Williamson said.

The names North and South had never been made official, a fact which was only discovered when the board met to discuss adopting Maori names for the country's two main land masses.

"While these names appear in official publications, including maps and charts, they had been recorded names only and had no formal standing," Williamson said.

"As an integral part of New Zealand's cultural identity and heritage, it is only right the names North Island and South Island be made official under the New Zealand Geographic Board Act 2008."

Williamson said his decision to assign alternative names meant people could use whichever they preferred and would not be forced to use both the English and Maori names together.

"Instead, everyone will have the choice to keep calling the islands what they always have, or use the assigned alternatives, or use both together if they wish," he said.

More:

Islands' alternate names confirmed