A central North Island iwi has lost a reported $29 million on bad investments and bailouts, and wiped almost half the value off its $66m Treaty settlement.

Ngati Tuwharetoa was part of the 2008 collective central North Island forestry claim that earned it, and six other iwi, a stake in a $400m-plus settlement dubbed the Treelords deal.

It is the largest agreement reached in Treaty settlements history.

Tuwharetoa Settlements Trust was set up to receive a cash payment of $66m, a share of 176,000 hectares of Crown forest land ($197m), 25.9 per cent of annual Crown forest licence fees ($2m to $3m a year) and a share of 3 million carbon credits.

Former National Party MP Georgina te Heuheu was one of six new trustees elected in December and, with its new general manager, Temuera Hall, found the accounts in disarray.

A forensic audit was commissioned and a special general meeting was held this month to alert beneficiaries to the multimillion-dollar loss, which sources inside the tribe said took the cash asset from $66m to $37m.

In a letter to the tribe, Hall said the new trustees would work to rebuild the faith and reputation of the trust within the tribe.

"This will be premised upon transparency, accountability, good communications, clear performance targets and strong cultural values," he said.

The trust had earned $12.4m in annual forest rentals since it was established in 2008 and $12.9m from its investment portfolio, but would see "impairments of up to $5m" for the current financial year, his letter says.

It has previously been reported that in 2008, the trust bailed out two tribal entities to the tune of $10.2m and secured a 649-ha block of land near Turangi after Te Whenua Venture Holdings went into liquidation.

It also advanced a loan to another tribal entity to gain control of a hotel with a $2.7m mortgage attached.

The 2008 Deed of Settlement required the trust to make payments to hapu trusts and $16.2m has been distributed so far. It had "a significant impact to the TST balance sheet" and forced the trust to reduce the level of grant funding available.

Since 2008, more than $12m had been distributed as education, kaumatua and general purpose grants, and special projects.

Grants were given towards the restoration of St Paul's Anglican Church in Tokaanu, $45,000 was available to 17 marae for maintenance and operational costs, and 400 homes were insulated in the past financial year.

Trust chairman Rakeipoho Taiaroa, who was also elected to the board in December, was unavailable for comment.