Despite pressure from the authorities to stop political activities, dissidents in Beijing have joined forces to condemn the detention of a veteran labour activist. Eighteen dissidents, including veterans Ren Wanding, Wei Xiaotao - brother of exiled Wei Jingsheng - Ma Shaohua, Chu Hailan, Zhou Guoqiang and Wang Hui, signed an open letter protesting against the detention of Zhu Rui. Zhu, 40, was taken away by four police officers in Beijing on Saturday. Earlier this month, she was detained for 10 days when United Nations Human Rights Commissioner Mary Robinson visited China. New York-based watchdog Human Rights in China said Zhu was held because officials wanted to stop her meeting Mrs Robinson. Police had not produced a warrant when taking Zhu away on Saturday, the group said. Her whereabouts remained unknown. The dissidents' letter said: 'We strongly protest against the authorities' wanton violation of citizens' personal freedom and their illegal persecution. We appeal to all Chinese people with a conscience, the international community and Mary Robinson to look into this case of rights violation and demand the immediate release of Zhu Rui.' Human Rights in China said Zhu's detention had aroused indignation among activists in provinces as far as Shaanxi, Zhejiang, Hunan and Guizhou. Many had contacted friends in Beijing to express concern. Zhu was a teacher at a school attached to a military clothes factory before she was laid off. Since then, she had organised protests with other laid-off workers. Another human rights group said Beijing activists were preparing to put forward three candidates for the local people's congress election in November. The candidates would be He Depu, Gao Hongming and Wang Zhixin, said the Hong Kong-based Information Centre of Human Rights and Democratic Movement in China. Although the constitution allows anyone to be elected as people's congress delegates, officials routinely bar dissidents from running in polls. The Paris-based World Association of Newspapers appealed for the release of dissident journalist Gao Yu, 55, who will have spent five years in jail on October 1. A letter to President Jiang Zemin urged him to release Gao on that date, the 49th anniversary of the People's Republic.