Three of China's most prominent liberal voices have started collecting signatures for a petition to demand the release of Xu Zhiyong, one of the founders of a civic movement calling for transparent and constitutional rule.
Octogenarian economist Mao Yushi, billionaire venture capitalist Wang Gongquan and veteran journalist Xiao Shu are the first three signatories of an open letter calling for Xu's unconditional release and an end to the persecution of the New Citizen movement.
The letter, drafted by Mao, also calls for an end to the obstruction of reporting on Xu's case. Since Xu's arrest on July 16, which has gone unreported in Chinese media, his name has been blocked from microblogs.
Xu, 40, a law lecturer at Beijing University of Posts and Telecommunications, was taken into police custody after spending three months under informal house arrest, sparking fears of a widening crackdown on human rights advocates under President Xi Jinping's new administration
He has gained widespread prominence as a founder of the New Citizen movement, which calls on the Chinese government to respect civil rights guaranteed to citizens by the nation's constitution. The movement also advocates for asset disclosures by government and Communist Party functionaries.
"We hope that Xu will be released," Wang told the South China Morning Post. "Perhaps the government doesn't fully understand the purpose of our citizen movement, but we have to make our voices heard."
Xu is not the first participant of the movement to be arrested for articulating these demands.
"Xu Zhiyong is now the 16th person detained for being involved in a citizens' campaign to press the government to get tough on corruption," said Maya Wang, a Hong-based researcher with Human Rights Watch.
"His detention shows the gulf between the government's stated intention on corruption, and its actions on the ground," she said.
The three initial signatories were among more than 100 intellectuals who had openly called on the incoming administration to ratify the International Covenant on Civil and Political Rights, a major international human rights treaty, in March.
The initiative comes a day after Wang Gongquan and Xiao Shu issued a statement  calling Xu's arrest "a sabotage of the legal system".
In their open letter, they vowed to continue Xu's activism: "We will continue to push ahead with the New Citizen's Movement within the boundaries of the constitution and the law, drawing on the fragile power we have as ordinary citizens."
"I expect there will be more people who will come out in support of Xu and the others who have been detained for calling for anti-corruption measures," said human rights researcher Wang.