The reasons for the blocks were unknown, but the move also comes after remarks by U.S. Secretary of State Mike Pompeo that the United States is “certainly looking at” banning Chinese social media apps, including TikTok.

South Korea’s communications regulator on Wednesday fined TikTok Pte Ltd, the publisher of the app, 186 million won ($154,320) for collecting personal information of children under 14 years of age without consent from guardians and failing to disclose or notify when sending personal information overseas.

TikTok was required to submit voluntary preventative measures within 30 days, and the regulator planned to continue discussions with TikTok on information security issues, an official with the Korea Communications Commission said.

Accounts of K-Pop stars such as Rain, TWICE, Mamamoo and HyunA were blocked from view on Douyin as of Friday.

Douyin and TikTok operated independently and the accounts were working normally on TikTok, a TikTok spokeswoman said.

Representatives for Douyin did not immediately respond to a request for comment. TikTok and Douyin are both owned by Chinese company ByteDance.

The K-pop stars’ management agencies did not comment.

China accumulated 196.6 million downloads of Douyin as of the first quarter of 2020, or 9.7% of more than 2 billion TikTok downloads in total, according to data from industry site Sensor Tower.

K-Pop concerts, tourism and South Korean businesses were hit hard by a Chinese boycott in 2017 after Seoul deployed a U.S-made missile defence system despite Beijing’s objections.

Hopes of a thaw in relations grew earlier this year amid plans for a possible visit to Seoul by Chinese President Xi Jinping.

($1 = 1,205.2700 won)

(Reporting by Joyce Lee in Seoul and Brenda Goh in Shanghai; Additional Reporting by Shanghai Newsroom; Editing by Stephen Coates)