By Supantha Mukherjee and Foo Yun Chee

STOCKHOLM/BRUSSELS (Reuters) - TikTok, Shein, Xiaomi and three other Chinese companies were named in a privacy complaint filed on Thursday by Austrian advocacy group Noyb, which alleged the firms were unlawfully sending European Union user data to China.

Noyb is known for filing complaints against American companies such as Apple, Alphabet and Meta, leading to several investigations and billions of dollars in fines.

Vienna-based Noyb (None Of Your Business) said this was its first complaint against Chinese firms.

Noyb has filed six complaints in Greece, Netherlands, Belgium, Italy and Austria seeking to suspend data transfers to China and is calling for fines that can reach up to 4% of a firm's global revenue.

Noyb said Alibaba's e-commerce site AliExpress, retailer Shein, TikTok and phone maker Xiaomi admit to sending Europeans' personal data to China, citing transparency reports and other documents, while retailer Temu and Tencent's messenger app WeChat transfer data to undisclosed "third countries", likely China.

The Chinese government "has never and will never" ask enterprises or individuals to collect or provide data information and intelligence located in foreign countries for the Chinese government in a manner that violates local laws, its foreign ministry said on Friday.

Ministry spokesperson Guo Jiakun said at a regular news briefing that China attaches great importance to and protects data privacy and security in accordance with the law.

A Xiaomi spokesperson said the company was examining the allegations and would fully cooperate with authorities to resolve the matter if they approach the company due to this complaint.

Other companies did not immediately respond to requests for comment.

Under the European Union's General Data Protection Regulation (GDPR) privacy regime, data transfers outside the EU are only allowed if the destination country doesn't undermine the protection of data.

"Given that China is an authoritarian surveillance state, it is crystal clear that China doesn't offer the same level of data protection as the EU," said Kleanthi Sardeli, a data protection lawyer at Noyb. "Transferring Europeans' personal data is clearly unlawful - and must be terminated immediately."

Chinese companies, notably ByteDance-owned TikTok, have been facing off with regulators in various countries. TikTok is planning to shut its app for U.S. users from Sunday, when a federal ban on the social media app is due to come into effect.

The European Commission is also investigating TikTok over its suspected failure to limit election interference, notably in the Romanian presidential vote in November.