UN human rights investigators demanded an end to a Chinese crackdown on lawyers on Thursday after more than 100 people were detained, intimidated or went missing over the past week.
The five independent experts said the crackdown may have broken the UN Declaration of Human Rights, the UN Basic Principles of the Role of Lawyers and China's own criminal procedures.
“Lawyers should never have to suffer prosecution or any other kind of sanctions or intimidation for discharging their professional duties,” they said in a statement issued by the UN human rights office.
Citing the need to buttress national security and stability, President Xi Jinping's administration has tightened its control over civil society since 2012. Amnesty International said 177 lawyers and activists had been detained or questioned by Wednesday, including 31 still missing or in police custody.
The People's Daily, the Communist Party mouthpiece, said last Saturday that the Fengrui law firm, several of whose lawyers have been detained, was a "major criminal organisation". The firm has been active in defending dissidents.
The detentions and questionings come after a months-long campaign in state media to discredit human rights activists for undermining national stability by using social media.
China has also been under fire for a new national security law that UN human rights chief Zeid Ra'ad al Hussein said "leaves the door wide open to further restrictions of the rights and freedoms of Chinese citizens". China said he was interfering in its affairs.
The latest crackdown targeted an "ever growing number" of law firm personnel and human rights defenders, mostly involved with human rights cases representing well known political dissidents, journalists and artists, the UN experts said.
Those arrested should be immediately released if there were no criminal charges against them, the UN investigators said.
The five experts hold mandates from the UN Human Rights Council to investigate the independence of judges and lawyers, the situation of human rights defenders, freedom of opinion and expression, freedom of peaceful assembly and association, and torture.
The European Union and United States have also criticised China's "systematic" detentions crackdown and called for the release of all those who had been detained.
The UN statement said the experts were in contact with Chinese authorities to "clarify the issues in question".
