BEIJING - China announced yesterday that it had recently arrested a prominent U.S.-based dissident, whom colleagues had reported missing in June while he was on a trip to Vietnam.

Wang Bingzhang, a permanent U.S. resident who lives in New York, was arrested on charges of espionage and "violent terrorist activities," said Xinhua, the Chinese government news agency, quoting a spokesman from the Ministry of Public Security.

The announcement gave few details of Wang's alleged activities, other than to accuse him of passing state secrets to Taiwan and posting essays on the Internet related to terrorist acts that threatened state security.

Such charges are extremely serious here because they are prosecuted under China's state secrets law, which calls for heavy sentences and deprives defendants of almost all legal rights. Xinhua said Wang's relatives had not been allowed to see him because the charges were brought under the state secrets law.

The Xinhua release said Wang and two other Chinese dissidents had been kidnapped in Vietnam and, July 3, were found by the police in China's Guangxi province, where they were being held captive. It did not explain who might have kidnapped them. Colleagues said the three were in Vietnam to meet with Chinese labor advocates. The other two members of the group, Yue Wu and Zhang Qi, had been investigated and cleared.

Since China joined forces in the U.S.-led campaign against terrorism last year, officials here have frequently tried to portray the detention and harsh treatment of a range of dissidents on domestic issues as antiterrorist activity, to the chagrin of human rights groups.

Wang, a longtime pro-democracy activist and critic of the Chinese government, went into exile in 1979 and has continued to press for change in China from abroad. In 1998, he used false documents to enter China illegally to lend his support to a fledgling pro-democracy party.