China says PM on TikTok is double-standard

China has labelled Prime Minister Scott Morrison joining social media app TikTok as a double standard.

Mr Morrison has previously warned Australians about the Chinese-owned app and said it "connects right back to China", but he joined on Christmas Eve.

Chinese foreign ministry spokesperson Zhao Lijian said Mr Morrison's choice of social media apps was "his own business", but added Australia should not discriminate against Chinese companies.

"I need to reiterate that the Australian side should follow the principle of openness and market rules, stop abusing the concept of "national security" or applying double standard to serve its interests, and provide a fair, open and non-discriminatory business environment for Chinese companies," he said.

Australia banned Chinese-owned tech giant Huawei in 2018 and has also cancelled a number of infrastructure deals citing security issues in China.

The prime minister posted two TikTok videos on Christmas Eve and has amassed more than 33,000 followers.