China on Friday detained key dissidents, placing some under house arrest amid growing calls for a tougher U.S. stance on Beijing's rights record ahead of World Human Rights Day. As rights activists and former prisoners of conscience gave testimony to a U.S. congressional hearing on human rights abuses in China, Beijing-based veteran democracy activist Zha Jianguo said he is now at home under tight surveillance. "They've been standing guard outside my door since early this morning," Zha said. "The police called me and said that tomorrow is World Human Rights Day, and that they'll be doing this for two days." "They said I mustn't go out," he said. "I said that's not OK, I have things to do, and you're going to deprive me of my basic right to freedom of movement on Human Rights Day?" He said he went out on Friday anyway. "They just followed me the whole time, until I had done what I needed to do and came home," Zha said. "They're still standing outside the door now." He said veteran political journalist Gao Yu, who was released from jail on medical parole earlier this year, is in a similar situation. In Washington, Jin Bianling, wife of disappeared rights lawyer Jiang Tianyong, says she is hoping U.S. politicians will step up the pressure on Beijing over her husband's whereabouts. "I am hoping that the leaders of the U.S. Congress will get in touch with the Chinese leadership and find out where my husband Jiang Tianyong is," she told RFA before attending a hearing on human rights run by the Congressional-Executive Commission on China in Washington. Jiang has been incommunicado, believed detained, since last month after visiting the family of detained rights lawyer Xie Dan in Changsha, Hunan province. "My husband bought a train ticket to go back to Beijing from Changsha on Nov. 21, and he sent out a social media post at around 10.22 p.m," Jin told reporters ahead of the hearing. "We haven't heard anything from him since." Hope Trump will be tougher She called on the Chinese government to release Jiang immediately. "If he is being held under residential surveillance, we want to know where he is," she said. "We also call on them not to torture him, and to take steps to take care of his health." Former Beijing University professor Xia Yeliang, who also attended the hearing, said many Chinese dissidents in exile are hoping for a tougher line on human rights under a Trump administration. "When Donald Trump becomes president of the United States, it's likely that we will see a shift in policy towards China," Xia said. "People of all ethnic groups have been targeted for persecution by the ruling Chinese Communist Party, and we want Congress ... to understand the serious failings of the current regime," he said. Veteran democracy activist Wei Jingsheng told the hearing that he fully supports president-elect Donald Trump's idea of a trade war with China, and that such an action should have been started a long time ago. "Since Chinese law does not guarantee human rights, it is able to keep labor prices at a very low level," Wei told the hearing. "This has led to the relocation of U.S. companies to foreign countries, while[it] also allows Chinese goods entering the US market with low prices, resulting in unfair competition," he said. "Pressure works' Anhui-based rights activist and former state prosecutor Shen Liangqing said the government routinely clamps down on politically sensitive figures around Human Rights Day, which is also the anniversary of the detention of jailed Nobel peace laureate Liu Xiaobo in 2008. "Of course it's highly inappropriate that they are violating human rights on Human Rights Day; it makes a mockery of it," Shen said. "But this is business as usual for the Chinese Communist Party. They have been doing this for years as part of their stability maintenance strategy." He said Chinese leaders care very little about international public opinion. "They don't care about all that: they just want to make sure that all remains quiet and that there are no signs of trouble," he said. But Uyghur dissident-in-exile Rebiya Kadeer said international pressure was the reason for her release from jail in 2005 on medical parole. "Let us be clear," Kadeer told the hearing. "Pressure works." She called on Beijing free jailed Uyghur scholar Ilham Tohti, his students and all Uyghur writers and reporters who contributed to his UighurBiz website. She also called on the Trump administration to "urge China to change its repressive policy, which is the root cause of all bloody incidents in Uyghur region." Human Rights Day falls on Dec. 10 every year, and was established in 1950 to mark the adoption of the United Nations' Universal Declaration of Human Rights two years earlier. It is frequently used as a focal point and key anniversary for political and human rights activists in China.