BEIJING - China's central bank said it would clean up various sorts of virtual currencies in 2018 in its latest effort to step up financial supervision.

Last September, Chinese authorities including the People's Bank of China (PBOC) ordered a ban on initial coin offerings, in which technology start-ups issue their own digital coins to investors to access funds, and shut down all virtual currency exchanges in the country.

The tough measures led to a sharp decline in virtual currency transaction volumes in China, according to Financial News, a publication run by the PBOC, the central bank.

PBOC deputy governor Fan Yifei said the bank will step up reform and innovation and continue to steadily carry forward the central bank's research and development of digital currency.

Fan made the remarks Wednesday during a teleconference on national work on currency, gold and silver for 2018.

To ensure order in the circulation of the Chinese currency, the renminbi, the PBOC will tighten supervision and strengthen quality management and control, according to an online statement released on Thursday.

More efforts should be made to serve the real economy and curb risks, and cash services will see further improvement with better infrastructure, Fan said.