A Chinese court Tuesday sentenced to five years in prison a Taiwanese activist who conducted online lectures on Taiwan’s democratization and managed a fund for families of political prisoners in China.

The Yueyang City Intermediate People’s Court in central China handed down the sentence against Taiwanese activist Lee Ming-che after finding him guilty of subversion of state power.

Lee’s co-defendant, Peng Yuhua, who is from mainland China, was sentenced to seven years’ imprisonment. Peng had also pleaded guilty during trial, saying he had founded an organization called Palm Flower Co. to pressure China to accept a multiparty political system. Lee was his deputy in charge of education, Peng said.

Taiwan, a self-governing island Beijing regards as part of Chinese territory, swiftly condemned the sentence.

“The spread of democratic ideas is innocent!” Alex Huang, the spokesman of Taiwanese President Tsai Ing-wen, said in a statement. Huang urged Beijing to release Lee as soon as possible and allow him to return to Taiwan.

“We cannot accept that Lee Ming-che has been convicted of ‘state subversion’ for sharing ideas of freedom and democracy out of concern for the development of mainland China’s civil society and democracy,” the statement said.

Lee’s trial marked China’s first criminal prosecution of a nonprofit worker since Beijing passed a law tightening controls over foreign non-governmental organizations.

Subversion of state power is a vaguely defined charge often used by authorities to muzzle dissent and imprison critics.

Lee was detained in southern China on March 19 and tried in September. Lee confessed to the charge during his trial, which his wife dismissed as “a political show.”

China’s wide-ranging crackdown on civil society has featured a string of televised “confessions” — believed to have been coerced — from human rights activists accused of plots to overthrow the political system.

Calls to Lee’s wife on her mobile phone rang unanswered.

The new law says foreign NGOs must not endanger China’s national security and ethnic unity, and places nonprofit groups under close police supervision. It is seen as an attempt to clamp down on perceived threats to the ruling Communist Party’s control.

Relations between Taiwan and China have been near an all-time low since the election of Tsai, whose party has advocated Taiwan’s formal independence. China cut off contacts with Taiwan’s government in June of last year, five months after Tsai was elected.