In Shanghai, one activist was detained yesterday and another is believed to have been in police custody since Sunday.
Mr Wang and another mainland dissident were arrested on Friday in central Anhui province. Mr Wang left China almost 20 years ago, but last month managed to sneak back in from Portugese-held Macau.
Mr Wang may have thought he could outwit China's state security apparatus, which is on a permanent state of high alert and keeps even low-level political activists under surveillance. It is likely the police were aware quite quickly that 50-year-old Mr Wang had entered China, but waited to see whom he contacted.
Dissident groups outside China yesterday said they expected more arrests.
Mr Wang appears to have residency status in the US, but not American citizenship. The US embassy in Peking yesterday said it was seeking information on Mr Wang's status and detention.
Any moves to form groups in China, either by political or union activists, are swiftly snuffed out by China's state security, despite Peking's protestations that the country is politically stable. It is unthinkable that a meeting of the planned organisation, to be called the Justice Party, could have taken place without state security knowing about it. China's leaders know that soaring unemployment probably makes the social environment fertile for sowing the seeds of political discontent. Millions of state enterprise workers, particularly in the north-east, are losing their jobs and finding that the old Communist social welfare system has disappeared.
In recent years, demonstrations by redundant workers have been treated relatively leniently, but any moves by activists to set up independent trade unions or workers groups have been crushed.
Mr Wang left China in 1978 to attend medical school in Canada. In the early Eighties he moved to the US where he started to publish a magazine called China Spring and formed a group for exiled Chinese dissidents. The two men who have now disappeared in Shanghai are Yang Qinheng, 44, who has already served five years in jail or labour camp, and Zhang Rujuan, who spent two-and-a-half years in prison.
Teresa Poole, PekingReuse content