U.N. human rights chief Volker Türk on Friday raised concerns over China’s newly adopted "ethnic unity” law, warning the legislation could restrict freedom of religion and cultural expression.

The law, passed Thursday by the National People's Congress, formalizes policies to promote Mandarin as the "national common language" in education, official business and public places.

Rights advocates warn the law could further marginalize minority groups such as the Uyghurs.

Turk is "concerned" by the law, his office said on X.

Turk warned that the law risks formally embedding assimilation policies that could undermine minority-language education and restrict the free practice of religion and culture. He said its provisions may place excessive limits on freedoms of expression, belief and assembly, while potentially penalizing the peaceful exercise of minority rights. He stressed that international human rights law obliges states to protect the identities and rights of ethnic, linguistic and religious minorities.

China's government has been accused for decades of pursuing policies to force assimilation across the vast country into the Han majority.

The law aims to allegedly "strengthen cohesion" within China, which the legislation argues is undergoing unprecedented social change.

China officially recognizes 55 official ethnic minorities within its borders that speak hundreds of languages and dialects.