China on Wednesday rejected as "irresponsible" comments by UN rights chief Zeid Ra'ad Al Hussein calling for the immediate release of rights lawyers and activists detained in the country.

Zeid on Tuesday raised concerns about the arrest of an estimated 250 lawyers and activists in a crackdown since July, warning that China appeared to be locking up government critics regardless of whether they had committed a crime.

But China said in a statement that "all those cases raised (by Zeid) involve illegal and criminal activities, and has nothing to do with restrictions of the rights and freedoms".

"The High Commissioner made irresponsible comments in disregard of facts," added the statement from Beijing's mission to the UN in Geneva.

Zeid made specific reference to the arrests of two prominent rights lawyers, Li Heping and Wang Yu, who were among a group of 15 lawyers arrested in July.

The Chinese statement said Wang and other "so-called 'lawyers'" were using a Beijing law firm as a front to organise criminal activity.

Regarding the prosecutions against employees of Hong Kong publishing house Mighty Current, which releases works critical of Beijing, China insisted all the cases were consistent with the country's criminal law.

Beijing also defended the arrest and subsequent expulsion of Swedish national Peter Dahlin, who had been held on charges of "endangering state security".

Responding to Zeid's criticism of the Dahlin case, the statement said the Swede was distributing misleading and distorted information about China's rights record to the international community.

"China is ruled by law and everyone is equal before the law," the statement said, charging that the UN rights chief had a "biased, subjective and selective" view of the country.