South Korea has accused Chinese AI startup DeepSeek of sharing user data with TikTok owner China.

“We have confirmed that DeepSeek is communicating with ByteDance,” the South Korean data regulator told Yonhap news agency.

The country, which has been plagued by data issues, had already removed DeepSeek from its app stores over the weekend.

China’s new January AI has sent shockwaves through the world, with its new model ChatGPT claiming to be cheaper to train than US doctors, sending global stock markets reeling.

In February, a US cybersecurity firm accused DeepSeek of sharing data with ByteDance, amid warnings that the data was not properly protected.

DeepSeek’s overnight App Store success has seen it climb to the top of charts in the UK, US and many countries around the world – it now sits well below ChatGPT in the UK rankings.

In South Korea, it had more than a million downloads before being removed from Apple and Google’s App Stores on Saturday evening.

Existing users can still log in and use it from a web browser.

The data regulator, the Personal Information Protection Commission (PIPC), told South Korea’s Yonhap news agency that it had found a link between DeepSeek and ByteDance, but it “has not yet confirmed what data was transferred and to what extent.”

Critics of the Chinese state have long argued that its national intelligence law allows the government to access data from Chinese companies for its own purposes.

However, Beijing-based ByteDance is among the global investors involved in the product — and some say the same law allows the private company to protect personal data.

Fears that data would be sent to China, the US has joined in confirming the TikTok ban, which was approved by the US.

President Donald Trump has sought to mediate a resolution, with the US ban set to expire on April 5.

Cybersecurity firm Security Mark published a blog post on DeepSeek on February 10 It suggested multiple direct links to “ByteDance Happiness.”

“These links suggest ByteDance’s analytics and performance monitoring infrastructure facilities,” it said in its review of DeepSeek’s Android app.

In a security risk assessment, DeepSeek raised concerns that “user behavior and device metadata may be sent to ByteDance servers.”

It also found that data “is transmitted to domains affiliated with Chinese government agencies.”

On Monday, South Korea’s PIPC found that “the traffic generated by third-party data transfers and the resulting lack of transparency in DeepSeek’s privacy policy” was “unacceptable.”

DeepSeek acknowledged that it was cooperating with the regulator and that it had failed to comply with South Korea’s privacy laws.

But the regulator advised users to “avoid accessing and sharing personal information linked to the chatbot.”

South Korea has already banned DeepSeek from government devices, with several countries including Australia and Taiwan following suit.

The BBC has contacted PIPC, ByteDance and DeepSeek’s parent company High Flyer for a response.