Last week, TikTok boss Shou Zi Chew was a guest of top EU politicians.
Discussions in Brussels focused on insufficient data protection, the spread of false information and content harmful to young people on the Chinese video platform.
The EU Commission has now threatened Shou with far-reaching sanctions if his company fails to comply with European rules in the future.
It is unacceptable that users can access dangerous and sometimes even life-threatening content via seemingly funny and harmless features within a few seconds, EU Commissioner Thierry Breton said on Thursday after a conversation with Chew.
He was also concerned about allegations that journalists were being spied on and that personal data was being transferred to locations outside Europe.
Sharp tones from Brussels
"I sent a very clear signal to TikTok CEO Shou Zi Chew that there is a need to step up our efforts to comply with EU legislation on data protection, copyright and online platforms," Breton said.
This applies in particular to the new EU law on digital services, which will apply to large platforms from September 1st of this year.
"We will not hesitate to decide on all possible sanctions if audits do not show full compliance," he added.
The new EU law also allows services in the EU to be banned in the event of repeated serious violations that endanger the life or safety of people.
A complete ban on the platform, which is used by more than a billion people, has already been discussed in the USA.
Sanctions were imposed on the Chinese network WeChat and TikTok while Donald Trump was still in office.
However, US President Joe Biden has withdrawn the decrees.
The Internet platform TikTok, which belongs to the Chinese Bytedance group, has long been criticized for insufficient data security and a lack of protection for young users.
It is feared, for example, that the Chinese state could have access to TikTok data.
TikTok denies that.