[SHANGHAI] China's property trusts, grappling with repayments equivalent to the size of Puerto Rico's economy, face rising default risks as a former central bank adviser dubs real estate the biggest threat to the economy.

The trust funds must repay 634 billion yuan (S$130.84 billion) of debt this year, up 50 per cent from last year, according to estimates from Haitong Securities Co, the nation's second-biggest brokerage.

The yield on the 2014 notes of Myhome Real Estate Development Group Co, based in the central city of Wuhan, jumped 185 basis points in the past year to 7.78 per cent. That compares with 3.13 per cent on property bonds globally, according to Bank of America Merrill Lynch indices.