Chinese human rights activist Wang Lihong went on trial in Beijing on Friday, witnesses said, nearly four months after she was arrested as part of a widespread crackdown on dissent. Wang, 55, a doctor and a veteran of China's pro-democracy movement in Tiananmen Square in 1989, was arrested on April 21 and is charged with creating a disturbance, the group Chinese Human Rights Defenders (CHRD) told AFP. Prominent artist and activist Ai Weiwei, recently released from detention, tweeted his support for Wang earlier this week. "If you don't speak out for Wang Lihong, you are not just a person who will not stand up for fairness and justice, you do not have self-respect," Ai wrote. Rights groups say Wang's charges are linked to her support for activists who used the Internet to call for Chinese citizens to join anti-government protests echoing unrest in the Middle East and Africa. The charge she faces carries a maximum sentence of five years imprisonment, Joshua Rosenzweig of the human rights group Dui Hua Foundation told AFP over the phone from Hong Kong. It is a catch-all charge used frequently in the last five to six years to silence anti-government protests, he said. "This particular crime or offence is somewhat notorious in the Chinese criminal code for being a pocket offence -- anything you want can be put into it," Rosenzweig said. Dozens of police were stationed outside the courtroom to keep about 30 protesters and Wang supporters in line, witnesses told AFP over the telephone. A core of supporters chanted "Wang Lihong is innocent!" outside the courthouse, they said. Among Wang's supporters outside the court was activist Zhao Lianhai, who was briefly jailed in Beijing in May for campaigning for victims of a 2008 tainted milk scandal that killed six children and sickened 300,000. Witnesses said police asked Zhao to leave the scene but allowed him to stay when he refused to go. Western diplomats hoping to observe the trial were kept waiting in a reception area and denied access to the courtroom, a representative from the Czech embassy told AFP. The diplomats included representatives from the United States, the European Union, Germany, Canada, Norway, Austria, the Netherlands and Switzerland. No journalists were allowed into the hearing.