Worries over deeply entrenched structural issues in China’s $21tn debt market are keeping foreign investors at bay, even as Beijing prepares to grant unprecedented access to local-currency bonds.

Global fixed-income traders sold about $35bn worth of renminbi-denominated bonds in the first four months of this year, and many are warning that the outflows will only get worse as concerns grow about poor liquidity — the ability to buy and sell the debt easily — and the country’s opaque process for resolving defaults.

The pressure on China’s bond market comes after years of steady international buying, and despite the government’s efforts to boost demand for domestic corporate debt through an upgrade of Hong Kong’s Bond Connect programme at the end of this month.