China's major coal firms reported widening losses for the first half of 2015 compared with a year earlier, and analysts said Monday that the trend will continue for the rest of the year because of continuing declines both in coal prices and demand.

More than 30 percent of 37 mainland-listed coal producers that released interim reports or earnings guidance incurred losses in the first six months, with many posting widening losses, Securities Daily reported Monday, citing data from HiThink Financial Services.

China Shenhua Energy, the country's largest coal miner in terms of output, posted a net profit of 11.73 billion yuan ($1.83 billion) in the first half of 2015, 45.6 percent less than a year earlier, according to its interim report released Saturday.

The report showed its profit from power generation exceeded that from coal production for the first time since the firm went public in 2005.

"Falling coal prices dragged down Shenhua's profit from coal production but boosted its profit from power generation," Deng Shun, a coal industry analyst with ICIS C1 Energy, told the Global Times Monday.

Shenhua outperformed most other Chinese coal firms. About 70 percent of China's large and medium-sized coal firms suffered widening losses in the first half of this year, Lu Junling, a senior official with the National Development and Reform Commission, said at a media briefing in late July.

China Coal Energy Co, the country's second-largest coal producer, reported a net loss of 965 million yuan in the first six months of this year - the first loss since its listing in 2008 - compared to a net profit of 912 million yuan in the first half of 2014.

Analysts said China's coal industry will continue to suffer losses in the second half, given the weakening demand, falling coal prices and the problem of overcapacity.

"Coal prices have been falling in the spot and futures markets, and are expected to stay near current low levels," Deng said.

In China, the price of coal has plummeted to 410 yuan per ton, down by around 20 percent since the beginning of the year. In the global market, the benchmark API2 2016 coal futures fell to a 12-year low of $52.85 per ton on August 18, Reuters reported.

"Coal prices may see a slight rebound in November and December due to higher seasonal demand, but that will not have a big effect in boosting coal firms' second-half earnings," Liu Jie, an analyst with Shandong-based commodity consultancy Sublime China Information, told the Global Times Monday.

But analysts said Chinese coal producers will face less pressure from their global rivals, as the yuan's depreciation of 4.4 percent against the US dollar since August 11 has increased the price of imported coal.

"Imported coal from Australia and Indonesia used to be 10-20 yuan per ton cheaper than domestic coal, but the yuan's devaluation has made imported coal lose its competitiveness," Liu said.

China imported 121.12 million tons of coal in the first seven months of this year, down 33.7 percent year-on-year, data from the General Administration of Customs showed.

Ivan Glasenberg, CEO of the world's biggest coal exporter Glencore, estimated during a conference call on Wednesday that China's coal imports would fall to about 130 million tons this year from about 200 million tons in 2014.