A cryptocurrency mine site in southwest China's Sichuan Province, August 12, 2016. /CFP

China's regulator has proposed phasing out domestic cryptocurrency mining in a document published on Friday, stepping up efforts to rein in the sector.

The National Development and Reform Commission (NDRC) added the sector to the 2021 negative list on Friday and is asking for public feedback.

The draft 2021 negative list covers 117 industries, six less than the 2020 list, according to the NDRC. Investing in sectors on the list is either banned or requires permits.

Citing concerns including energy-wasting and regulation, officials included cryptocurrency mining on an April 2019 preliminary list of industries China wanted to eliminate. However, it was removed from the final version of the list published in November 2019.

The crypto market has drawn regulatory attention, as the highly volatile digital currencies pose growing risks. China in September banned cryptocurrency transactions and prohibited opening new mining projects in the country. It had also barred financial institutions and payment companies from providing services related to cryptocurrency transactions in May.