Followers of the Shincheonji Church of Jesus gathered at the Wuhan church despite becoming aware of a potential health threat, the South China Morning Post reported.
"Rumours about a virus began to circulate in November but no one took them seriously," one member, who wasn’t identified, told the outlet.
It’s unclear whether there was any interaction between the Wuhan followers and those at the Daegu congregation in South Korea, where hundreds of members have fallen ill with the virus.
Around half of South Korea’s 977 cases were traced to the church, which was shut down in an effort to stop the spread of the virus.
The Shincheonji Church, which mainstream South Korean congregations consider a cult, centers around the personality of its chairman, Lee Man-hee, who followers believe is immortal, the BBC reported.
Members sit on the floor tightly together during services, which one official said could have fueled the spread of the virus.
"There is a possibility that the characteristics of many people sitting close together in a very confined space and holding service for more than an hour [would have led to] a few who were exposed infecting many other infectees," Jung Eun-kyeong, director of the South Korean Centre for Disease Control, said, according to the BBC.
South Korea’s death toll from the virus climbed Tuesday to 10, while there were more than 213 new confirmed cases.