New Zealand Post has agreed to sell its 35% stake in Datacom Group to the New Zealand Superannuation Fund for $142 million to repay debt and bolster its capital.

The state-owned postal service had its credit rating cut to A+ from AA- in October as it searches for new revenue streams in the face of dwindling demand for traditional postal services. It will get a net gain of $76.4 million from the sale of Datacom.

"Having a significant amount of capital locked up in a minority shareholding does not meet the currency strategic needs of the New Zealand Post Group," chief executive Brian Roche says. The sale of shares in Datacom "is a move out of necessity given other capital priorities" within the group.

The funds will be used to restructure the group's debt position and fund strategic investments, he says.

NZ Post's profit rose 38% last year, mainly driven by record returns from its Kiwibank subsidiary. Postal revenue fell by $17 million as kiwis posted 54 million fewer letters.

Datacom is an IT services provider with 4000 staff across 13 sites in the Asia Pacific region, including 2000 in New Zealand. Datacom's major shareholder is NBR Rich Lister John Holdsworth.

NZ Post will remain a significant customer of Datacom, it said. The deal requires approval from the Australian Foreign Investment Review Board.