The value of bonds issued in China last month totaled 3.8 trillion yuan (about 587 billion U.S. dollars), up from 3.6 trillion yuan in April, official data showed Tuesday.

Treasury bond issuance stood at 315.1 billion yuan, while local government bond issuance was 355.3 billion yuan, according to the People's Bank of China (PBOC).

Financial bonds issued last month were valued at 513.8 billion yuan, and corporate debenture issuance was 382.9 billion yuan.

By the end of May, total bonds outstanding reached 78.6 trillion yuan.

China has the world's third largest bond market, which is growing rapidly and opening wider to overseas investors.

Risks on the country's bond market are overall controllable, the PBOC said in a statement Monday, commenting on recent bond defaults.

The new defaults emerged after regulators toughened up supervision, while the bond default rate was low, the statement said.

Last year, China issued bonds worth 40.8 trillion yuan, up 12.9 percent from the previous year, according to PBOC data.