Metallurgical coal production was down 14% from the previous record June quarter, attributable to planned maintenance and the impact of unseasonal wet weather in Queensland.

Illawarra Coal achieved record quarterly production due to the reduced impact of longwall changeouts during the period.

A total of 9.57 million tonnes of metallurgical coal was produced, with BMA output of 5.9Mt, Illawarra producing 2.2Mt and BHP Mitsui at 1.45Mt.

The Goonyella operation in Queensland was the biggest producer of metallurgical coal with 1.68Mt for the quarter, with the Blackwater mine closely following with 1.4Mt.

BHP said third party rail and port constraints continued to impact Queensland sales, with the company expecting the limitations to continue in the near term.

On energy coal production, BHP said scheduled maintenance at the Navajo mine in the US and poor geological conditions at New Mexico's San Juan longwall impacted production. San Juan produced 963,000t during the quarter.

However, this was offset by record quarterly production from Hunter Valley mines and Cerrejon Coal in Colombia.

As with metallurgical shipments in Queensland, third party constraints continued to impact Hunter Valley export sales.