China's coal imports declined 37.5 per cent over the first six months of the year, in apparent confirmation that "quality restrictions" were being used as a protection measure for the struggling local industry.

Data released by China's Customs Bureau on Monday showed the country imported 99.87 million tonnes of coal in the first six months of the year.

On a monthly basis, imports rose slightly in June to 16.6 million tonnes from May, but this was still below the average monthly level for 2015.

Data released by China's Customs Bureau on Monday showed the country imported 99.87 million tonnes of coal in the first six months of the year. Reuters

Iron ore imports rose 5.7 per cent on a monthly basis in June, as higher cost domestic producers shut down and were replaced by cheaper imports from Australia and Brazil.

The value of China's overall trade fell 6.9 per cent in the first half of the year, due to a dramatic slide in imports.