Shares in miner Rio Tinto (LON:RIO) edged up on Wednesday morning, after reporting an increase in iron ore and copper output in the first quarter.

Pilbara iron ore volumes increased by 8 percent to 83.1 million tonnes on-year, with copper output up by 65 percent to 139.3k tonnes as operations recover from the strike in Chile.

However hard coking coal production struggled during the quarter, falling 30 percent to around 1.1 million tonnes, negatively affected by maintenance works at the Kestrel mine.

Production of titanium dioxide slag also declined by 12 percent, with annual guidance cut slightly to between 1.1 and 1.3 million.

The company said in a statement: “We delivered a solid operational performance across most commodities in the first quarter of 2018”.

“Our world-class Pilbara iron ore assets continue to demonstrate flexibility and the benefits of increased productivity, and production at our bauxite and copper assets was also higher.

“By continuing to advance our mine-to-market productivity programme, whilst maintaining our focus on the disciplined allocation of cash, we will continue to deliver superior returns to our shareholders.”

Shares in Rio Tinto are currently trading up 2.20 percent at 3,858.00 (0823GMT).