Police in southern China detained feminist activist and journalist Huang Xueqin after she returned to the mainland from Hong Kong and Taiwan, her friends said Friday.

Authorities in Guangdong province's Guangzhou city arrested Huang last Thursday on suspicion of "picking quarrels and provoking trouble," her friends said. The vague charge is commonly used against activists viewed as threatening by the ruling Communist Party.

The friends spoke on the condition of anonymity because they feared government retribution for being publicly associated with Huang. Calls on Friday to Huang's lawyer and Guangzhou's Baiyun District Detention Center, where friends say she is detained, rang unanswered.

The friends said police harassed Huang's family after she published an essay describing her experience at a protest in Hong Kong, a semi-autonomous Chinese city that has been roiled by months of anti-government demonstrations.

"Perhaps, under the powerful machine of the party state, ignorance and fear can be cultivated," Huang wrote in her essay. "But if you have personally experienced it, witnessed it, you cannot pretend to be ignorant."

In August, Guangzhou police confiscated Huang's passport and other travel documents, preventing her from pursuing a postgraduate law program at the University of Hong Kong.

Huang has been an outspoken voice in China's #MeToo movement, helping sexual assault victims highlight cases against university professors. She has worked as an independent reporter covering issues surrounding gender, equality and disadvantaged groups.

Detained, harassed

"It is unclear exactly the reasons for Huang's detention, but in recent weeks, more and more activists, writers and regular citizens in the mainland have been detained or harassed by authorities for their peacefully voicing support for the Hong Kong protests," said Yaqiu Wang, China researcher at Human Rights Watch.

"Huang's detention shows that the Chinese government has intensified the crackdown on mainland Chinese who peacefully showed solidarity with Hong Kong protesters, and that authorities are fearful that the protests in Hong Kong could inspire challenges to the government in the mainland, and any expression of ideas of freedom and democracy is a threat to their grip on power," Wang said.

The protests in Hong Kong began over the summer in response to a now-withdrawn extradition bill that would have allowed Hong Kong residents to stand trial in mainland China, where critics say their legal rights would be threatened. The sometimes-violent demonstrations have since ballooned to encompass broader calls for democratic reform and an inquiry into alleged police abuse.