Authorities in the southern Chinese province of Guangdong this week briefly detained a prominent women's rights activist linked to a campaign to help the daughter of a leading dissident who is held under house arrest, her husband and rights lawyers said. Su Changlan was detained on Tuesday at her home in Foshan city, but no reason was given for her detention, her husband, who gave only his surname Chen, told RFA's Mandarin Service. Su was released later that day, after questioning likely linked to her involvement in a campaign for Zhang Anni, daughter of Anhui-based dissident Zhang Lin, to be allowed to attend school, lawyer Sui Muqing said. "Su Changlan has just been taken away by the Foshan police," Chen told RFA's Mandarin Service on Tuesday. "There were two of them, and they didn't give a reason." "She was taken away by a state security officer from Nanhai[district] and a Foshan police officer," he said. Su had been a volunteer for the New York-based rights group Women's Rights in China, and had campaigned vigorously for the political, economic and social rights of women and girls. Sui, a Guangzhou-based lawyer, said Su had taken part in a number of politically sensitive campaigns since last year, including campaigning in the Anhui capital Hefei for Anni, who was barred from attending school last year. Anni has since moved to the United States to continue her education, and her father, a veteran pro-democracy activist who previously served 13 years in prison on subversion charges for his political activities, stood trial in December on public order offenses. "Su Changlan ... went to[Anhui provincial capital] Hefei last year, and when the police detained[fellow activist] Tian Li, they kept asking about the incident in Hefei, and what part they had played in it," Sui said. Chen said he guessed that the detention could have something to do with a visit Su made to Anhui last year. "It seems like she got into an altercation with someone higher up," he said. Beijing-based rights lawyer Liu Xiaoyuan said he is acting for Su's fellow activist Tian Li, and that he had received a number of phone calls from Su's family on the day of her detention. "I think it's about the Anni incident, because Su Changlan and Tian Li went to Anhui together," Liu said. "But it's ridiculous if they are still detaining people over Zhang Anni." He said Anni's father Zhang Lin was still awaiting sentencing following a mid-December trial in Anhui's Bengbu city. "They can't sentence him, and it seems they have postponed it, because there are other cases linked to Zhang Lin's still with the prosecutor, but they can't back out now," Liu said. Dubbed "China's youngest political prisoner," Zhang Anni was held under house arrest and removed from two schools, sparking protests that she was being punished for her father's activism. Now at school in the United States along with her sister Ruli, Anni has written to U.S. President Barack Obama, Chinese President Xi Jinping, the U.S. Congress and the European, British, and Canadian parliaments, saying that the charges against Zhang Lin are "groundless."