Eighty-two of the 106 arrested in the past four days have since been released, the Hong Kong-based Human Rights Lawyers Concern Group said late on Sunday.

But at least three of those were taken away for a second time, a lawyer told the South China Morning Post.

China’s Ministry of Public Security said on its website that the detained lawyers were a “major criminal gang” who had “seriously disturbed order”.

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Since July 2012, the group has organised more than 40 controversial incidents and severely disrupted public order, it said.

It also accused the lawyers of using the Beijing Fengrui law firm as a platform to raise awareness about sensitive cases, in order to “extort money in fundraising” from online campaigns and overseas donors and “create social chaos.”

‘Bad cultural influences’

It included an alleged confession from a detained activist admitting that they had caused trouble and were “proud of being detained”.

The ministry’s accusations signal a “new reality” under the leadership of President Xi Jinping, said Sophie Richardson, China director at Human Rights Watch.

“Beijing has long made clear its hostility towards lawyers who try to challenge authorities, but to allege that they are part of some crime syndicate is a new and disturbing tactic,” Richardson said.

It the largest crackdown on lawyers since 2011, when some lawyers were arrested or beaten in the wake of anonymous calls for protesters to stage a pro-democracy “jasmine revolution” in China, Amnesty International said.

The arrests started after a lawyer at the Fengrui firm, Wang Yu, went missing early on Thursday. Yu had defended clients such as Uighur economist Ilham Tohti, who has been sentenced to life imprisonment, and activist Cao Shunli, who died in prison last year.

By Friday, at least five employees of the Fengrui law firm went missing, with some “forcibly taken away” by either police or unidentified men, fellow lawyers said on Twitter.

Others detained included Beijing-based rights lawyer Li Heping, who had represented high-profile clients such as blind advocate Chen Guangcheng, reports said.

Another prominent rights lawyer, Sui Muqing, was detained in the southern city of Guangzhou after police told him to go outside because something had happened to his car, according to Amnesty’s China researcher William Nee.

On Saturday, Sui was put under “residential surveillance at a designated location”, which can last up to six months for alleged “incitement to subvert state power,” the South China Morning Post reported.

It was unclear whether the lawyers and activists will be charged with any crimes.

Nee said the arrests could be connected to a sweeping national security law approved by China’s legislature this month.

The far-reaching, vaguely worded legislation empowers the state to take “all necessary measures” to protect its sovereignty, and calls for defence against “bad cultural influences”, “malignant groups” and “criminal activities under the guise of religion”.

“It is too early to tell but the national security law could have given the government more confidence to round up these people,” Nee said.

The new law could lead to additional crackdowns on civic freedoms, UN human rights chief Zeid Ra’ad Al Hussein said in Geneva last week.

Hussein said the law does not properly define what constitutes a security threat.

“As a result, it leaves the door wide open to further restrictions of the rights and freedoms of Chinese citizens, and to even tighter control of civil society by the Chinese authorities than there is already.”