Authorities in the southwestern Chinese region of Guangxi have detained outspoken rights attorney Tan Yongpei, whose license to practice was revoked last year.

Tan was detained on Thursday by officers of the Nanning municipal police department during a raid on his Baijuying legal consultancy company.

An employee at a company occupying the same floor told RFA: "There were 10 or 20 of them. They came shortly after 5.00 p.m., just before we got off work."

"They showed their police identification and said they were from the police department and that they were looking for a lawyer surnamed Tan," he said. "Then they went in."

The employee said the officers were still on the premises when he left after 6.00 p.m. "They were forceful, but went into their offices quite politely, with somebody shooting video," he said. "They put seals on Tan's office door that said "Nanning Municipal Police Department."

The Civil Rights and Livelihood Watch website said the police hadn't produced any official documents authorizing the raid and search, however.

It said Tan had tried and failed to prevent them from carrying out the raid, which lasted around three hours, after which the police took Tan away with them.

Fellow Guangxi-based lawyer Tan Jiaji said it was hard to tell whether Tan would face criminal charges now, or simply be released after questioning.

"It's pretty hard to say right now," he said. "Anything is possible."

"He would regularly post [politically sensitive] stuff to social media, so maybe they now see him as a threat," Tan Jiaji said. "This sort of thing is happening more and more nowadays."

"I wasn't surprised at all that this happened."

'Picking quarrels and stirring up trouble'

He said the authorities can use catch-all charges like "picking quarrels and stirring up trouble" to detain people for what they post to social media.

"The whole idea of what is picking quarrels and stirring up trouble is so broad," he said. "It's perfect for those in power to use [against government critics]."

In January, Tan's China Lawyer's Club was raided by dozens of police office who said it was an illegal organization of banned lawyers.

A nationwide police operation under the administration of President Xi Jinping has targeted more than 300 lawyers, law firms, and related activists for questioning, detention, imprisonment, debarring and travel bans since it launched in July 2015.

The China Lawyers' Club was set up in Guangxi's regional capital, Nanning, by a group of former rights attorneys who lost their "business license" at the hands of local justice departments, and may no longer represent clients in court.

Formally established on Sept. 29, 2018, the club's aim was to find employment and income for dozens of experienced litigators who no longer have an income in the wake of the crackdown.

The club traded as a legal services company, and had 'signed' lawyers in a manner similar to the way sports teams sign big stars. Under current regulations, Chinese lawyers need a business license to represent clients, but not to offer legal consultancy on petitions and complaints.