Rights group Amnesty International issued an appeal in the cases of five members of an underground Protestant church sentenced to death in China.
"Amnesty International is concerned that the five sentenced to death may have been tortured to force them to confess," the appeal said Wednesday.
The case comes amid concerns by rights groups that a government crackdown on the Falungong group and other similar Buddhist-based organisations has been extended to underground Christian churches.
The United States has raised concerns about the repression of Christians such as the recent jailing of Hong Kong businessman Li Guangqiang for trying to smuggle 16,000 Bibles into the China.
"We find it a deplorable sentence and a deplorable charge," US Secretary of State Colin Powell said Tuesday.
Five members of the South China Church were given death sentences on December 29 by the Intermediate People's Court in Jingmen city, in the central province of Hubei, a criminal court official told AFP at the time.
Twelve other members were sentenced to between two years and life imprisonment, the official said.
Church founder Gong Shengliang was sentenced to death for "using an evil sect to harm the implementation of the law" as well as "premeditated assault" and "crimes of rape and hooliganism", the official said.
The Hong Kong-based Information Center for Human Rights and Democracy reported that Gong's niece, Li Ying, was sentenced to death with a two-year reprieve for printing copies of a church publication.
Amnesty on Wednesday named Xu Fuming, Hu Yong and Gong Bangkun as the three others sentenced to die, with Gong Bangkun's sentence suspended to two years.
Under Chinese law death sentences with a reprieve are commuted to life if the period in question is served with good behaviour.
Amnesty said its concerns about torture were prompted in part by reports that three young women also connected with the church had endured serious physical abuse when arrested last year.
In letters to their families later made public, Zhang Hongjuan, Li Tongjin and Yang Tongni said abuse had included beatings with electric batons and belts.
Yang and Li were reported to be serving three-year terms at a labour camp in Hubei, while the whereabouts of Zhang were unknown, Amnesty said.
Relatives of two of those facing death sentences, Li Ying and Xu Fuming, have publicly appealed to authorities to review the cases, Amnesty said.
"Even at this very moment we still don't know the whereabouts of our loved ones, how their life is, whether they are still healthy, even whether they are still alive or what awaits them eventually," they were quoted as saying.
China permits Christian worship but only through tightly-controlled "official" Protestant and Catholic churches.
However underground churches flourish, with some estimates saying as many as 10 million people worship at unofficial Protestant groups alone.