Wellington, May 18 NZPA - State-owned coal miner Solid Energy is ordering a further $65 million of plant and equipment for its Stockton opencast mine, north of Westport.

Solid Energy has already ordered $75m worth of equipment to upgrade the mine's core mining fleet, the company said.

The latest contracts, for Caterpillar machinery and Haulmax trucks from Gough Gough & Hamer Ltd, will be delivered later this year.

The investments in machinery and trucks, about $15m in infrastructure upgrades, and $124m to design and build a coal handling and processing plant, take Solid Energy's investment in Stockton to nearly $280m in the last 18 months.