The Chinese government's decision to ban imports of lower quality coal, or "dirty" coal, from 2015 could affect a major portion of Australia's coal exports to China, experts said on Tuesday.

Australia exports an estimated 50 million tons of thermal coal a year to China, which could be at risk with the ban.

The Chinese government has started to limit the use of imported coal with more than 40 percent ash and 3 percent sulphur, in an effort to improve air quality in its major cities.

Consultant Wood Mackenzie told media that it estimated that the Chinese ban could affect more than half of Australia's thermal coal exports to China.

"Our product is typically around 5500 kilo calories and 24 to 25 percent ash. So we've got big problems," Bruce Jacques of IHS McCloskey Coal said.

However, the Minerals Council of Australia said the new rules would have little impact on Australian exports.

"There is nothing in the information released to date to suggest that Australian coal exporters will be disadvantaged and we are confident that we can meet the proposed specifications," Minerals Council executive director of coal Greg Evans told media.

"Australia is fortunate to have reserves of high quality black coal, which will continue to be in strong demand from established and emerging markets, including China."