At least 146 lawyers, activists and their relatives have been taken into custody or questioned by police in 24 Chinese cities and provinces over the past few days, according to the China Human Rights Lawyers Concern Group
, a Hong Kong-based organization that monitors and promotes the rule of law on the mainland.
At least 22 people remain in custody, the group says.
The Chinese police defended the massive round-up, telling state media they targeted a "criminal gang" suspected of illegally organizing paid protests.
As of Tuesday, the Hong Kong lawyers group says at least 124 of the detainees have been released.
Among those who were briefly detained and questioned by police was Feng Zhenghu, a veteran human rights activist based in Shanghai.
"The government asked us not to poke our nose into this business, to ignore the missing lawyers," Feng told CNN.
"They wanted us to know that they don't want us to post or repost anything on this matter on the Internet," he added, pointing out that he has been detained and questioned dozens of times by Chinese authorities in just the last two years.
"The authorities must end this assault against human rights lawyers," human rights watchdog Amnesty International said
in a statement.
One of the targets in the police raids was the Fengrui Law Firm in Beijing, which employs several prominent lawyers known to take on politically sensitive cases involving human rights activists.
An employee -- who asked not to be named for fear of reprisals from the authorities -- told CNN more than a dozen police searched the firm's offices on Friday. The employee said at least ten of the firm's lawyers, including director Zhou Shifeng, have been held in police custody.
The Ministry of Public Security, China's national police, accuses the Fengrui lawyers of "trying to create social conflict by using paid protesters, trying to influence public sentiment and spreading rumors."
In a statement, the ministry accused the lawyers of organizing more than 40 incidents that "severely disrupted public order" over the past three years. Chinese officials claim the law firm used these cases to promote its profile, in an attempt to then charge clients higher fees.
The ministry linked lawyers from the Fengrui Law Firm to protests over a deadly incident on May 2, in which a police officer shot dead an unarmed man at a railway station in northeastern China.
Chinese authorities argue the police officer fired in self-defense.
Accused of "illegal operations"
The Ministry of Public Security accused Fengrui Law Firm lawyers of spreading false stories about the incident and working with an internet dissident who allegedly made an on-line offer of the equivalent of $16,000 to anyone who could provide video of the police shooting. State broadcaster CCTV has also aired footage of a suspect confessing to police details of their cooperation with human rights lawyers in such "illegal operations."
Among the lawyers detained in recent days was a female Fengrui associate named Wang Yu.
The Hong Kong-based Chinese Human Rights Lawyers Concern Group says Wang sent a text message at 3 a.m. on Thursday July 9 after the electricity and Internet connection in her Beijing home abruptly went out.
A little more than an hour later, Wang sent a followup message saying someone was "trying to pry her door open." When colleagues tried to reach her at dawn, her house was empty and she was no longer answering her phone.
Police also detained Wang's husband and son, though the 16-year-old boy has since been released.
Lawyer: Arrests part of smear campaign
"It's nonsense," said the Fengrui Law Firm employee contacted by CNN, when asked about the accusations against his colleagues. He accused officials of a smear campaign against human rights activists.
This is not the first time Chinese security forces have rounded up critics of the government. But activists have long painted an increasingly grim picture of human rights abuses under the leadership of President Xi Jinping.
Since he came to power in late 2012, Xi has been accused of tightening his grip on any open dissent. Recent examples of prominent figures being arrested and imprisoned on what critics say are trumped-up charges included Gao Yu, a 71-year-old veteran journalist, and Ilham Tohti
, an ethnic Uyghur economics professor known for his moderate views on ethnic issues in China.
Despite frequent statements of support for rule of law in China, critics say Xi appears to have shown little mercy to lawyers that the government considers to be troublemakers.
Pu Zhiqiang, a famous human rights lawyer whose advocacy contributed to the abolition of China's notorious labor camp prison system, was arrested
in June 2014 on charges that included "picking quarrels and provoking troubles". He is still awaiting trial.
This month, Beijing approved a new national security law that broadens the definition of potential threats to the country.
Washington referenced the new law in a statement condemning the detention of human rights lawyers.
"We are deeply concerned that the broad scope of the new National Security Law is being used as a legal facade to commit human rights abuses," the State Department said in a written statement.