China produced around 584,000 mt of refined copper in April, down 1.6% month on month, an official from state-owned nonferrous metals information division Beijing Antaike said Wednesday, citing National Bureau of Statistics data.

The April output was up 5.2% year on year, he added.

Over January-April, output totaled 2.24 million mt, up 6.4% year on year.

The figures were not yet available on NBS' website.

The Antaike official said the month-on-month drop was due mainly to lower output from Tongling Nonferrous Metals and Jinchuan Group.

Tongling's 400,000 mt smelter was shut for maintenance in April, while Jinchuan's plant was undergoing repairs after a technical problem with its oxygen-producing machine in March.

Oxygen is essential for copper production and Jinchuan expects the repairs will take around four months to complete.

Jinchuan has a capacity to produce 600,000 mt/year of refined copper.

The Antaike official added that the year-on-year increase in copper output was in tandem with a rise in the country's capacity.

China's copper capacity is expected to rise to around 10 million mt in 2014, up about 11.1% from 2013.