The investment arm of South Island based iwi Ngai Tahu is buying into agricultural services company PGG Wrightson.

Ngai Tahu Holdings is taking a $15 million cornerstone shareholding in a joint venture vehicle with Singapore and China-based investment businesses.

Chairman Trevor Burt said the proposition made good commercial sense and it was another opportunity for the company to diversify its portfolio of investments.

Ngai Tahu has extensive business interests in the South Island including commercial, tourism, seafood, property and rural ventures.