Taipei, Mar 19 (IANS): The health of Taiwanese pro-democracy activist Lee Ming-che, sentenced in 2017 to five years in jail for subversion of state power, is at risk in the Chinese prison where he is being held, Human Rights Watch (HRW) warned on Tuesday.

On the second anniversary of Lee's arrest, human rights groups in Taiwan and abroad said that the 44-year-old's health has deteriorated since he was imprisoned, reports Efe news.

In a statement, HRW said China has "forcibly disappeared and prosecuted citizens of other countries for helping Chinese activists or speaking critically of the government".

Among those are "Swedish activist Peter Dahlin, British bookseller Lee Bo and Swedish bookseller Gui Minhai, whose whereabouts remain unknown", the statement added.

The activist has been transferred twice to different prisons and is forbidden from sending letters or receiving books, including those that meet government approval, says HRW.

His wife, Li Ching-yu, has only been allowed to visit him six times since his imprisonment even though the country's Prison Law allows prisoners visits by family members at least once a month.

Lee, a volunteer with the Taiwan-based NGO Covenants Watch, was sentenced in November 2017 for having "online discussions about transitional justice and democracy in Taiwan and sharing books on human rights with friends in the mainland", the HRW said.

Lee, a former member of Taiwan's ruling Democratic Progressive Party, is a professor at the Wenshan Community College in Taipei.

He had disappeared mysteriously in March 2017, after entering China from Macau while on a private visit and his whereabouts had remained unknown until May, when Chinese authorities had said they had detained him on suspicion of subversion of state power.

Lee's case marks the first-ever extraterritorial trial against critics of China.

He is also the first Taiwanese dissident charged with subversion of state power as well as the first non-Chinese member of a non-governmental organisation, who was tried in China after a new law, that aimed to regulate nonprofits in the Asian country, was approved in 2016.