China has capped outstanding local government debt at 21 trillion yuan for 2018, the ministry said in its annual budget report released in March.

Local governments have ramped up issuance of special bonds over the last few months, with data from the People's Bank of China on Wednesday showing they issued 738.9 billion yuan of special bonds in September.

That compared to 410.6 billion yuan sold in August.

In the first half of the year, more than 300 billion yuan of special bonds were issued, a pace the finance ministry described as "slow".

The special bonds are usually issued to fund spending on public investment projects.