``The Chinese government has blatantly broken the promises it made by signing international human rights covenants in continuing to suppress political dissent,'' an open letter to to the United Nations and western governments, signed by 205 activists across China, said.

It said the crackdown showed the `hypocrisy' of the Chinese government.``It is obvious that China has no sincerity in improving its human rights situation,'' said the letter, a copy of which was received by AFP.

Liu, 48, a former labour activist, was released after more than three years in prison to seek medical help in the United States.

``Liu Nianchun's long-awaited release is welcomed. But many more are being detained, imprisoned and stripped of their basic human rights,'' the New York-based Human Rights in China (HRIC) said in astatement.

Liu Qing, who works at HRIC, told AFP by telephone his younger brother's release did not mean the authorities had eased pressure on pro-democracy activists.

``The Chinese Communist Party is not loosening up at all. It's just that international pressure through the media and other channels sometimes makes them feel they should respond,'' he said.

Liu's release comes just one day ahead of the trial of prominent Beijing-based activist Xu Wenli on charges of subversion, and within days of two other dissident trials on similar charges.

CDP founder Wang Youcai was tried on Thursday in the eastern city of Hangzhou for ``attempting to overthrow state power'', while Qin Yongmin, a CDP activist and close associate of Xu, was in court on the same charges in central Wuhan.

Both courts closed on Thursday without returning a verdict or announcing further court sessions, amid furious allegations by the men's relatives that they had not been given the chance to defend themselves properly. Another CDPmember, Xu Wanping, was sentenced to three years in a ``labour re-education camp'' by the authorities in the south-western city of Chongqing, dissidents aid Saturday.

President Jiang Zemin on Friday vowed to `nip in the bud' any attempts to destabilise the state politically or socially.

His speech, marking the 20th anniversary of the economic reforms launched by late paramount leader Deng Xiaoping, quashed any hopes he might seize the occasion to announce political reforms.

China signed the international agreement on civil and political rights in October and its sister covenant on economic, social and cultural rights last year, but has yet to ratify either treaty.