Yanzhou Coal Mining Co Ltd, China's fourth-largest producer of the fuel, announced a provision for impairment losses of $343 million amid weak demand both domestically and abroad, the company said in a filling to the Hong Kong stock exchange on Monday.

In the first half of 2013, the group realized sales of about 24.44 billion yuan ($3.9 billion) for its coal business, representing a decrease of about 2.97 billion yuan, or 10.8 percent, compared with the same period in 2012, the statement said.

Its subsidiary, Yancoal, also slid into the red, with a net loss of A$749 million ($687.9 million) for the first half of this year, according to its financial report.

In sharp contrast, the Australian coal producer declared a net profit of A$409.5 million for the same period last year.

Yancoal said that it had allocated an impairment, or asset write down, to its Moolarben and Stratford and Duralie mines in New South Wales.