The United Nations human rights office on Friday denounced China's “ongoing crackdown” and detention of lawyers and activists and called on authorities to release all those being held for exercising what it called fundamental freedoms.

It voiced concern at reports that defence lawyer Chen Jiangang and his family were taken by police on Wednesday while travelling in the southwest province of Yunnan. His whereabouts remained unknown, though his wife and two children were released.

Mr. Chen represents Xie Yang, a lawyer in custody since July 2015 whose trial had been due to begin last week on charges of inciting subversion and disrupting court order, U.N. human rights spokeswoman Ravina Shamdasani said in Geneva.

“Prior to being reportedly taken by police last Wednesday, Chen had, in a video message, expressed concerns that he too may 'lose his freedom' and that he may be coerced into self-incrimination,” Ms. Shamdasani told a news briefing.

“We are dismayed by this continuing pattern of harassment of lawyers, through continued detention, without full due process guarantees and with alleged exposure to ill-treatment and coercion into self-incrimination,” she said.

The vast majority of detained lawyers were defending citzens' basic economic, social and cultural rights, she added.

Since 2015, dozens of people linked to a Beijing law firm have been detained or prosecuted by the authorities in a crackdown on dissent. China consistently rejects criticism of its human rights record and says it is a country ruled by law.