China announced Monday a 3 percent tax on imports of steam coal with low calorific value but is yet to spell out details of its applicability, leading to uncertainty whether shipments from top low-grade supplier Indonesia will be subjected to the tariffs.
Indonesia is the biggest seller to China of lignite, a form of low-grade coal, with its shipments accounting for 97 percent of China's total lignite imports in 2013 up to end of July.
Moves by China, the world's top coal buyer, to slap an import tariffon lignite may dent sales of Indonesian miners such as Bumi Resources and Adaro Energy and could spark defaults of existing contracts.
China's State Council, the country's cabinet, last week approved a plan to implement a 3 percent tariff on lignite imported from countries under the most-favored nation trade status, the Ministry of Finance said in a statement.
Lignite previously enjoyed zero import tariff.
The statement did not specify what grades of lignite, in terms of heating value per kilogram, would be affected.
However, trade sources questioned if China would be able to impose import tariffs on Indonesian coal, since a free trade agreement between China and the Association of Southeast Asian Nations has brought import tariffs for lignite to zero since the start of 2012.
The import tax on other coal has been scrapped since 2008.
With imported lignite currently priced at about $47 a ton on a landed basis, the newly imposed tariff would add about $1.31 a ton to its cost, industry sources said.