The wife of a Taiwanese rights activist being held in China arrived in the mainland Sunday on the eve of his trial in a case that has further soured cross-strait relations. Lee Ching-yu, wife of NGO worker Lee Ming-cheh who has been held incommunicado in China for more than 170 days, left for Shanghai around noon to connect to a flight to the central province of Hunan where her husband's trial will be held. "We landed and are on our way to our hotel in Yueyang city," Xiao Yimin, a Taiwanese legal activist accompanying Lee, told AFP. "As we understand, she will be allowed in court, but we don't know if the rest of us will be able to get in," said Xiao, who is general secretary of the Judicial Reform Foundation. Lee's trial is set to start Monday at a court in Hunan's Yueyang city, according to his wife. The activist's mother arrived in Yueyang Sunday evening. Both women were accompanied by several officials from Taiwan's semi-official Straits Exchange Foundation, which handles relations with the mainland. Lee went missing during a visit to the mainland in March and Chinese authorities later confirmed he was being investigated for suspected activities "endangering national security". Lee Ching-yu made no comment at the airport but has pleaded for Taiwanese people to understand if her husband is "forced to confess" in court. "I go to (China) not to provoke or argue. I hope to see the arrival of justice and let Lee Ming-cheh return to Taiwan safe and soon," she told reporters before leaving on Saturday. She attempted to fly to Beijing in April to "rescue" her husband but Chinese authorities at that time revoked her travel permit. Xiao told AFP that Lee was unavailable to speak with media Sunday night. Their supporters shared a video on social media Sunday saying it showed workers setting up roadblocks outside the Yueyang courtroom. - 'No evidence of wrongdoing' - Beijing has repeatedly ignored Taipei's requests for information on Lee's whereabouts and details of the allegations against him. Relations between the two sides have worsened since Taiwanese President Tsai Ing-wen took office in May last year. Since then Beijing has cut off all official communications with Taipei. China sees self-ruled Taiwan as part of its territory waiting to be reunified. It wants Tsai to acknowledge the island is part of "One China", which she has refused to do. Lee has long supported civil society organisations and activists in China, according to Amnesty International. He had shared "Taiwan's democratic experiences" with his Chinese friends online for many years and often mailed books to them, said the Taiwan Association for Human Rights. "We urge the Chinese authorities to allow Lee's wife to attend the trial tomorrow," Amnesty International China researcher Patrick Poon told AFP. "Lee hasn't been given any access to his family and a lawyer of his choice since he was detained in March. Such practice does not meet international standards on fair trial," Poon added. Sophie Richardson, China director of Human Rights Watch, told AFP that Beijing had provided "no evidence of actual wrongdoing" in Lee's case. "The charges should be dropped immediately and he should be allowed to return home," Richardson said.