BHP Billiton Ltd.'s iron ore production for its fiscal year first quarter remain unchanged, growing to only one per cent from a year ago.

In a statement released on Wednesday, the world's largest mining company said it churned out a total of 39.77 million metric tonnes of the key steelmaking ingredient in the three months ended Sept. 30, compared with the 39.57 million tonnes the previous year.

Albeit the marginal rise, the September output was still three per cent lower over than the June quarter.

BHP attributed its September churn out to a planned shutdown related to harbour expansion work.

"Western Australia iron ore sustained strong performance in the September 2012 quarter despite the impact of a planned shutdown associated with the Inner Harbor expansion project," BHP said in the statement, adding first ore was loaded in the quarter from two new shiploaders at Nelson Pt. in the harbor.

Coal

The global miner's metallurgical coal production, meanwhile, dropped year on year by 4 per cent to 8.94 million tonnes. It was however a jump of 10 per cent versus the previous quarter.

"Queensland Coal production increased by 20 per cent during the September 2012 quarter as significant latent capacity was released across the supply chain," BHP said.

"Production at BMA benefited from a reduction in industrial activity with no significant work stoppages experienced since July 2012."

Energy coal production, meanwhile, was up by six per cent.

Petroleum, Others

BHP's output of petroleum products jumped 19 per cent in the three months to September from a year ago, supported by the resumption of work in the Gulf of Mexico, including the reduction of maintenance work on some Australian operations.

Copper and lead production dropped 24 per cent and 6 per cent, respectively, in the September quarter from the previous corresponding period.

Zinc production jumped 11 per cent from the previous period as well as uranium production by 4 per cent. Silver production was steady.