BHP Billiton has maintained its full-year production guidance for most commodities including iron ore after reporting a first-half boost in production of copper and energy coal.

The global miner lifted copper production by 17 per cent in the six months to December, compared to the prior first half, while iron ore volumes were flat and petroleum and metallurgical coal volumes were down.

BHP chief executive Andrew Mackenzie said the improved production had allowed the company to benefit from higher commodity prices in the half.

The company has cut guidance for metallurgical coal and flagged cost impacts after encountering problems at some of its Queensland mines but Mr Mackenzie pointed to a broadly improved second half across all its businesses.

“Together with incremental production from latent capacity projects in iron ore and copper, we expect volume growth of six per cent for the full year,” he said in a statement to the ASX on Thursday.

The resources giant produced 117 million tonnes of iron ore in the six months to December 31, flat compared to a year ago, but copper output rose 17 per cent on the back of a jump in volumes at its Escondida mine in Chile, and energy coal rose four per cent thanks to a strong performance at NSW Energy Coal.

BHP blamed a seven per cent fall in petroleum volumes on the impact of Hurricane Harvey and Hurricane Nate on its US petroleum assets and natural field decline.

Metallurgical coal also slid, by four per cent, with record production at four of BHP’s Queensland coal mines offset by lower volumes at it the Broadmeadow and Blackwater mines in the Bowen Basin.

The company has maintained its full-year production guidance for petroleum, copper, iron ore and energy coal.

But, BHP has revised down its metallurgical coal production forecast due to challenging roof conditions at the Broadmeadow mine and engineering issues triggered by wet weather impacts at the Blackwater mine, both of which are 50:50 per cent owned with Mitsubishi.

The mining giant also flagged that underlying earnings in the half are expected to include impairment charges, mainly related to conveyors at the Escondida mine, of between $US250 million and $US350 million ($A350 million and $A490 million).

BHP shares closed four cents, or 0.1 per cent, higher at $30.78.