One of Germany's data protection watchdogs on Friday said DeepSeek's app illegally sends user data to China and asked Google and Apple to consider blocking the artificial intelligence service.

Berlin's data protection commissioner Meike Kamp said in a statement that DeepSeek's transfer of German user data to China is "unlawful."

There is not a readily available way to get in touch with DeepSeek. CNBC has reached out to DeepSeek's privacy team.

Chinese firm DeepSeek made waves this year when it launched an AI model that it claimed was created at a fraction of the cost of competitors, using less advanced Nvidia chips.

The company also has its own global chatbot AI app, which has been downloaded millions of times, garnering scrutiny.

If the German case against DeepSeek progresses, it could lead to a European Union-wide ban for the app, some experts say.

"It is certainly possible that this incident could lead to an EU-wide ban because the rules that apply in Germany are the same elsewhere in the EU and also in the UK," Matt Holman, specialist AI and data lawyer at Cripps, told CNBC by email. There are a few steps before this would become reality, however.

"DeepSeek has not been able to convincingly demonstrate to my authority that the data of German users is protected in China at a level equivalent to that of the European Union," Germany's Kamp said, according to a CNBC translation. "Chinese authorities have extensive access rights to personal data within the sphere of influence of Chinese companies."

Under the European Union's General Data Protection Regulation — the bloc's huge data protection law — companies are prohibited from sending data outside the region unless specific safeguards are in place at the countries of arrival. Those safeguards must meet GDPR requirements in Europe.

In short, the Berlin data protection commissioner is concerned that Chinese authorities could access German user data sent by DeepSeek to China.

The Berlin data watchdog on Friday said it had informed Apple and Google of DeepSeek's alleged violations and expects the U.S. tech giants to carry out a "timely review" about whether to ban the app or not from their respective app stores.

It's unclear if Google and Apple will comply. CNBC has reached out to both companies for comment.

Cripps' Holman said that while and EU-wide ban is possible, there needs to be consensus among the bloc's regulators first that this would be an appropriate step.

If Apple and Google remove DeepSeek from their app stores, this would effectively amount to an EU-wide ban, Holman said.

"The implications for Deepseek could be, unsurprisingly, quite stark. Access to German citizens' data will be curtailed. In short order this could expand to the remainder of the EU if other national regulators follow suits meaning EU — and potentially UK — markets will be curtailed if Apple and Google disables the app," Holman said.

This is not DeepSeek's first run-in with regulators in Europe. Italian data protection authorities in February ordered DeepSeek to block its app in the country. Meanwhile, Irish authorities in January asked DeepSeek for information on its data processing.