A Vatican-affiliated news agency says China's government-backed Catholic church is expected to ordain another bishop without the Pope's approval.
Today's ordination would be Beijing's third without a papal mandate in eight months.
The Vatican insists that only the Pope has the right to appoint bishops. Beijing sees this as interference in its affairs.
AsiaNews said Father Joseph Huang Bingzhang will be ordained in Shantou in Guangdong province and four bishops who have been held "for days" by government representatives will be forced to attend.
Papal adviser Hong Kong Cardinal Joseph Zen appealed to China's president Hu Jintao and premier Wen Jiabao to stop the ordination.