Chinese authorities are racing to prevent the default of a soured $500m high-yield investment trust, in a closely watched test case for the country’s shadow banking sector.

Local media reported on Thursday that the Shanxi provincial government is considering helping fund a bailout of the trust loan after ICBC, which distributed the product through its branches, said last week it would not provide a backstop. However, Time-Weekly, a state-owned newspaper, reported that the bank – the world’s biggest by assets – and the product issuer China Credit Trust will also be asked to chip in.

The Rmb3bn ($500m) loan, to a now-defunct Shanxi coal mining company, is due to be repaid on January 31. When it was packaged as a trust product and sold in 2010, it promised investors a yield of 10 per cent. However, in 2012 it became clear that the company, Zhenfu Energy, was struggling for cash after the coal sector was hit hard by Beijing’s efforts to reduce pollution levels across the country.