The United States and 11 other countries took China to task at the United Nations on Thursday over its human rights record and demanded it immediately release all detained activists and lawyers.

"We are concerned about China's deteriorating human rights record, notably the arrests and ongoing detention of rights activists, civil society leaders and lawyers," US ambassador Keith Harper told the UN Human Rights Council in Geneva.

Speaking on behalf of Australia, Britain, Denmark, Finland, Germany, Iceland, Ireland, Japan, Norway, the Netherlands, Sweden and the United States, Harper said that in many cases, those detained "have not been granted access to legal council or allowed visits by family members."

"These actions are in contravention of China's own laws, and international commitments," he said.

Harper came out in support of comments by UN human rights chief Zeid Ra'ad Al Hussein last month raising concerns about the arrest of around 250 lawyers and activists in a crackdown since July 2015.

In comments harshly criticised by Beijing, Zeid said China appeared to be locking up government critics regardless of whether they had committed a crime, and demanded it release those detained "immediately and without conditions."

Harper echoed the call, urging China "to release all rights activists, civil society leaders and lawyers detained for peacefully exercising their freedom of expression or for lawfully practising their profession."

The US ambassador to the UN rights council also raised concerns over "the unexplained recent disappearances and apparent coerced returns of Chinese and foreign citizens from outside mainland China".

"These extra-territorial actions are unacceptable, and out of step with the expectations of the international community and a challenge to the rule-based international order," Harper said.

Five booksellers from Hong Kong's Mighty Current publishing house, known for its salacious titles critical of Beijing, for instance went missing last year.

They all later turned up on television in mainland China to say they had not been abducted, with some providing tearful confessions that they had been smuggling illicit books into the country.

Harper voiced concern over "the increasing number of individuals whose confessions have been aired on state media prior to any indictment or judicial process".

"These actions run contrary to fair trial guarantees enshrined in China's laws, and counter to the rights and freedoms set out in the universal declaration of human rights."