A Beijing college student has written to China's president calling for the release of her classmate currently under criminal detention for sending out a tweet linked to the 25th anniversary of the military crackdown on student-led protests in Tiananmen Square.
Beijing International Studies University student Zhao Huaxu, 22, was detained after she sent out a May 24 message on Twitter that linked an article she wrote about "fake base stations," a type of equipment that can be used to broadcast SMS text messages to large numbers of cell phone users nearby.
The link suggested ways to use the equipment to tell more people about the anniversary and the 1989 bloodshed, a topic that is censored from China's Internet and rarely discussed in public.
Zhao's article also warned that the ruling Chinese Communist Party regards them as illegal, and anyone using them to send out messages could be held on criminal charges.
Police confirmed Zhao's detention on suspicion of "teaching methods for committing a crime" on June 9, the Chinese Human Rights Defenders (CHRD) group said in an e-mailed statement late on Thursday.
In an open letter to President Xi Jinping, Zhao's classmate Tang Lu called for her immediate release.
"Zhao Huaxu, a second-year student at the same college as me, suggested via Twitter how we might spread the truth about the June 4, 1989 massacre," Tang wrote.
"Why are you so afraid, to the extent that you detain a young woman for writing a couple of lines about it on the Internet?" the letter said.
Beijing-based rights activist Hu Jia called on Zhao's college for more information.
"We and some other friends would like to know much more from the Beijing International Studies University about the situation," Hu said.
He said he and other activists are currently in the process of finding a rights lawyer on behalf of Zhao's family, to represent her.
Zhao's friends had been told she was sick, he said. "Zhao Huaxu is ill in the hospital, and hasn't been to class for a while, is what we've been hearing from her friends," Hu said.
Repeated calls to the Beijing International Studies University offices rang unanswered during office hours on Friday.
An employee who answered the phone at the campus security department declined to comment, however. "Sorry, this is just the campus security center of operations," he said.
Chinese authorities have detained dozens of rights activists, political dissidents, lawyers, and journalists in the weeks running up to the 25th anniversary of the June 4 bloodshed.
While many have been released or allowed to return home from enforced "vacations" in recent days, others remain behind bars facing criminal charges.
A lawyer for veteran Beijing-based journalist Gao Yu said he had recently applied for permission to visit her in a detention center.
Gao was under criminal detention on charges of "leaking state secrets" and paraded on the state television channel, where she was shown, her face blurred on screen, apparently confessing to having obtained a highly confidential document and sent it to an overseas website.
"We know very little right now, because I haven't been able to meet with her," Gao's lawyer Zhang Sizhi told RFA on Friday. "We asked about visiting her on Monday ... but it's Friday already and we haven't had a reply from them."
"We will ask again next week," Zhang said.
Gao, who played an active part during the Tiananmen Square protests, was detained on June 3, 1989, as the People's Liberation Army (PLA) moved its tanks into the heart of Beijing, firing on civilians and putting a bloody end to calls for greater democracy and rule of law.
She was released after 450 days but jailed again in November 1994 for "illegally providing state secrets to institutions outside China's borders," in connection with four articles she wrote in the Hong Kong-based Mirror Monthly magazine.
More recently, she has given outspoken interviews and written commentaries for overseas media, including RFA, and also worked for Germany's Deutsche Welle radio service.
Reported by Qiao Long for RFA's Mandarin Service and by Hai Nan for the Cantonese Service. Translated and written in English by Luisetta Mudie.