Mr. Chen is the third person in recent days to be charged with inciting subversion in an extraordinarily harsh crackdownon progressives in China that has been unfolding since late February.The other two, Ran Yunfei and Ding Mao, are also from Sichuan and areknown, like Mr. Chen, to be promoters of the rule of law anddemocracy-oriented reforms.

Parts of Sichuan Province, a rugged, populous area in western China, areknown to be havens for liberal thinkers, and the region has a longliterary and philosophical tradition. The authorities there are now atthe forefront of pressing charges against people advocating politicalreform.

On Friday, a court in Sichuan sentenced Liu Xianbin,a veteran democracy activist, to 10 years in prison for slandering theCommunist Party in his writings; Mr. Liu was detained in June, beforethe current clampdown.

The recent wave of disappearances and detentions began when aChinese-language Web site hosted in the United States posted a call inlate February for frustrated Chinese to take to the streets in aso-called Jasmine Revolution to protest corruption and unjust rule. TheChinese government, fearing the kinds of protests that have sweptthrough the Arab world, has apparently ordered that any signs of dissentbe nipped in the bud.

China Human Rights Defenders estimates that at least 23 people have been detained for criminal investigation. ChinaGeeks.org, an English-language Web site based in Beijing, compiled a listthis week of about 50 Chinese who have been recently detained, arrestedor made to disappear; the list is based on various reports and isincomplete.

One person on the list is Yang Hengjun,an Australian spy novelist and pro-democracy blogger who vanished onSunday after reportedly making a call from the airport in the southerncity of Guangzhou. Mr. Yang had said three men were following him. TheAustralian government said Tuesday that it was concerned about Mr.Yang’s whereabouts, and one friend in Australia said Mr. Yang, a formeremployee of the Chinese Foreign Ministry, had indicated over the phoneto his sister that he had been taken away by security officers.

On Wednesday, the mystery over Mr. Yang deepened when at least threefriends of his said on their microblogs that he had called them thatmorning to say he was in a hospital. One friend, Li Huizhi, wrote thatMr. Yang had said everything was a “misunderstanding.” Another friend,Wu Jiaxiang, told Reuters that Mr. Yang coughed a few times. “It’simpossible for me to say whether Yang was really in the hospital,” hesaid.

The cryptic calls have fueled theories among many of Mr. Yang’ssupporters that he was being held by the state at a secret site.