China's digital economy accounts for nearly a third of gross domestic product, according to a report released at an annual cyberspace conference staged by the government to justify its strict internet censorship.

Beijing this year has dramatically strengthened its already tight regulation of the internet, but officials and local media have used the fourth World Internet Conference to declare Chinese cyberspace is "open" -- but subject to controls for the greater good.

The report unveiled on Monday in the eastern city of Wuzhen by the state-linked Chinese Academy of Cyberspace Studies, said China's digital economy reached 22.58 trillion yuan ($3.4 trillion) in 2016, according to conference organisers.