Three Chinese journalists have been detained or harassed by police in recent days amid a nationwide crackdown on activists and political dissent.
Guangdong-based journalist Wang Sijing was forcibly detained by Wuhan police after she traveled there to cover a story about psychiatric hospital inmates, she told Twitter users.
Wang, who writes for the 21st Century Economic Report, was released after her mobile phone was confiscated, but declined to comment on Friday.
"It's not convenient for me to talk right now," Wang said. "But I'm fine. Thanks to everyone for their concern."
Wang had traveled to Wuhan to follow up on reports of petitioners in the city who complained of being locked up as psychiatric patients.
Petitioners Hu Guohong and Cheng Xue were incarcerated in a Wuhan mental hospital after they helped expose the case of a third petitioner, Xu Wu, who was also treated as mentally ill.
Xu Wu, a former worker at the Wuhan Iron and Steel (Group) Corp. (WISCO), had been petitioning the authorities over unequal pay in his company.
Locked in a room
Following her release, Wang reported having been locked in a room at Wuhan's Hanjiang district police station to friends and Twitter followers, who relayed the news via the microblogging service.
Hanjiang police station chief Liu Hanwen denied that police had detained Wang against her will, however.
"She called us, and the response team went to find out what was happening," Liu said. "How can you say that we detained her? This is a mistake."
"Nobody stopped her from carrying out reporting activities."
Rights lawyer Si Weijiang said that if Liu's account was true, then police should also have taken the person Wang was complaining about to the station for questioning.
"Also, the police shouldn't confiscate someone's mobile phone," Si said. "This wasn't an item used to commit a crime."
Rights group 'concerned'
The New York-based Committee to Protect Journalists (CPJ) said it is also concerned about the fate of two Chinese journalists who reported on detained artist and social critic Ai Weiwei.
It named Caijing magazine journalist Zhang Jialong and freelance journalist and documentary filmmaker Wen Tao as "missing" and believed detained for questioning.
Zhang tweeted that he had returned home on Friday, however.
"Thanks to all my friends on Twitter for their concern," he wrote in the first tweet since April 28. "I have now returned home."
"Rare good news," tweeted the Chinese Human Rights Defenders (CHRD) group on hearing of Zhang's release.
However, Wen Tao was still "missing and believed detained since April 3," the CPJ said in a statement on its website.
Others detained
"The disappearance of ... journalists who were reporting on Ai Weiwei and other Chinese activists is deeply concerning," said CPJ Deputy Director Robert Mahoney.
"We fear they are the latest victims of the Chinese Communist Party's efforts to stifle the flow of independent information."
Chinese authorities have detained a series of journalists and online commentators since anonymous calls for anti-government demonstrations appeared on Chinese-language websites in February, inspired by unrest in the Middle East and North Africa, the CPJ said.
"Some of those detained, such as online writer Ran Yunfei, now face criminal prosecution," it said.
"Internet censorship has tightened since the crackdown, which has also extended to professional Chinese journalists, ethnic minority websites, and the foreign press," the statement said, citing CPJ research.
Reported by Xin Yu for RFA's Mandarin service, and by Wen Yuqing for the Cantonese service. Translated and written in English by Luisetta Mudie.