Attributable iron ore production for the nine months to March 31 was 1% lower at 171 million tonnes.

Western Australian iron ore (WAIO) production increased by 2% to a record 193Mt.

Despite that, full-year guidance for WAIO was reduced by 10Mt to 260Mt (on a 100% basis) due to adverse weather and the initiation of an accelerated rail network maintenance program.

The company said the renewal program would deliver an increase in system capacity to 290Mtpa over time.

C1 cost guidance for WAIO was maintained at $US15 per tonne.

Global iron ore guidance for FY16 on an attributable basis is now 229Mt, down from 237Mt reported in January, and 247Mt initially targeted for the year.

Despite flat to slightly lower production across copper, coal and petroleum, full-year guidance was maintained.

BHP said it was on track to deliver an average unit cost improvement at 14% across its major assets.

CEO Andrew Mackenzie said despite adverse weather, productivity was improving.

“Over the last 12 months, we have taken a number of steps to strengthen BHP Billiton, including asset sales and the deferral of investment for long-term value,” he said.

“While these measures will reduce our output this year, they have increased our focus on our highest-quality operations and will support stronger margins and returns.”

Mackenzie said BHP had an opportunity to grow the value of the company by simplifying the organisational structure, adopting new technology and debottlenecking.

“We have a pipeline of projects in copper and oil that allow us to bring high-margin volumes to market when the time is right,” he said.

“And as others cut back on exploration, our investment will go further and help create new options for the future.”

The company announced a $640 million exploration program for the petroleum division to fund additional access and testing of future growth opportunities.

BHP shares rose 2.3% to $A20.13, a 2016 high.