Dissidents and families of victims of the brutally suppressed June 4, 1989, democracy movement yesterday continued their demands for redress while authorities moved to silence talk about the event on the Internet. Open discussion about the massacre remained taboo - 11 years after troops crushed the movement centred on Beijing's Tiananmen Square, killing hundreds of demonstrators. But a few dissidents registered their defiance yesterday by issuing open letters through overseas human rights organisations. One was Liu Xiaobo, branded a 'black hand' behind the 1989 movement. He urged authorities to free other dissidents still in jail. Mr Liu was stunned by the story of a little-known dissident, Chen Lantao, who was sentenced to 18 years for giving a speech in 1989 and was released only recently, the Hong Kong-based Information Centre for Human Rights and Democracy said. Formerly a university lecturer, Mr Liu said the case of Mr Chen, a student in Shandong province before his arrest, exemplified the large number of unnamed dissidents still in prison. Families of victims who died or were injured in the crackdown should be compensated and donations from abroad should not be banned, he said. Mr Liu served 18 months for his part in the 1989 movement. In 1996, he was again sent for 're-education through labour' - a form of administrative detention - for demanding the impeachment of President Jiang Zemin. He was released last year. Also vocal were nine labour activists from Liaoning province who issued a similar letter to Mr Jiang, according to the human rights group. The activists who signed the letter could not be reached yesterday. The centre said previous attempts to ask for a review of the June 4th movement, as in the case of Beijing-based activist Jiang Qisheng last year, often resulted in imprisonment of review advocates. Families of the June 4 victims also sent public letters through overseas human rights groups asking that 'justice be done' over the crackdown in Tiananmen Square. In stark contrast to the advocacy, the buzz within online chatrooms quietened down as the June 4 anniversary neared. Frequent visitors to popular chatrooms posted warnings asking fellow 'chatmates' to avoid leaving sensitive messages about June 4 on the Internet. Yesterday, some messages in chatrooms claimed that Internet portals had received warnings from police to delete messages about the 1989 movement as well as the recent murder of a Beijing University student, Qiu Qingfeng. The death of Qiu triggered two days of protests by more than 2,000 students last week. While the protest was not politically motivated, it rattled the nerves of authorities who feared any incident which might revive the memory of the student movement 11 years ago since Beijing University had been a hotbed of student activism in the capital.