Construction workers in west Auckland have unearthed a treasure trove of rare and valuable swamp kauri.

Photo: Supplied

While carbon dating is yet to be carried out, swamp kauri are prehistoric trees which can be buried for anywhere between 800 and 50,000 years under peat swamps in the North Island.

At one time it was valued at over $10,000 per cubic metre, making it one of the most expensive timbers in the world.

More than 20 pieces of the wood measuring up to seven metres in length and almost one metre diameter had been sealed in a chemically balanced environment at the Henderson site and are extremely well preserved.

It was found at a depth of about four metres by workers laying the foundations of a new shopping complex.

It was immediately recognised by assistant site manager Lisa Wade as swamp kauri and, after months of excavating, it's now being donated to local Māori carvers will

from Wananga o Aotearoa in Māngere, who will turn it into pou whenua.

"Tāne Mahuta, the Māori God of the forests and birds, was said to be made of kauri making this taonga particularly precious to the Māori people," Ms Wade said.