Among them are two activists, Wang Zecheng and Wang Wenjiang, who had collected more than 100 signatures in support of demands for the release of the first four dissidents.

The second batch of dissidents were taken from their homes in the northern Liaoning province on Friday night.

On Monday night, veteran pro-democracy activist Xu Wenli was taken from his Beijing home.

He has already spent 12 years in prison and was recently nominated as the head of the Beijing branch of the China Democracy Party (CDP).

Beijing says the dissidents have broken the law which forbids the setting up of opposition parties.

Detentions condemned

Foreign governments and human rights groups in China and abroad have said the move shows that attempts to stifle political opposition have been stepped up.

The US State Department spokesman, James Rubin, described it as "a serious step in the wrong direction".

He said the matter had been raised with the Chinese authorities, and added: "We have said for some weeks now that we are disturbed by the recent number of detentions of dissidents that serve to limit political debate in China."

Crackdown on democracy party

Activists who recently founded a CDP branch in the central city of Wuhan were also detained on Monday.

These included Qin Yongmin, a close ally of Mr Xu, and two others, according to a Hong Kong-based dissident group, the Information Centre of Human Rights and Democratic Movement in China.

The centre suggested that the detentions were in response to a meeting in Wuhan last week of local members of the CDP.

Another party member was also reported to have been detained in the eastern city of Hangzhou, where attempts to establish China's first independent political organisation began this summer.

The Hong Kong centre said it believed the latest moves could herald a tougher line from authorities concerned at growing support for the group. In the past, activists have been questioned, but the majority later released.