Thirteen of the country's 30 nickel mines had no output last year, the Mines and Geosciences Bureau (MGB) said in a report.

The Southeast Asian country's output of nickel ore, most of which is shipped to China to make stainless steel, totalled 23.35 million dry metric tonnes (DMT) compared with 24.95 million DMT in 2016.

Gold output fell 2 percent to 22,699 kilograms, while silver production was down 10 percent at 31,748 kgs.

Production of copper concentrate dropped 16 percent to 280,394 DMT.

The country's metal output last year was valued at 108.64 billion pesos ($2.08 billion), up 5.7 percent from the previous year as prices rose amid tight supply and robust demand, the MGB said.

Mining is a contentious issue in the Philippines, which has vast but largely undeveloped mineral wealth, because of environmental mismanagement by some miners.

The sector accounts for just less than 1 percent of the overall domestic economic output, with only 3 percent of the 9 million hectares believed to have high mineral reserves being mined, according to government data.