Leaders of underground Chinese Protestant churches condemned the government's persecution of a fellow congregation, while Catholics voted under the watchful eye of security forces for a new government-approved bishop, reports said.

The developments illustrate growing tensions between Communist authorities and increasingly assertive Christian groups whose memberships are growing rapidly.

While China's Constitution guarantees freedom of religion, Christians are required to worship in churches run by state-controlled groups. However, tens of millions of Christians are believed to worship in unregistered "house" churches which receive varying degrees of harassment.

In Beijing, underground Protestant church leaders issued a petition to the National People's Congress, China's rubber-stamp legislature, calling for an end to persecution of Shouwang Church and its 1,000 members who have been blocked from their worship place in Beijing in recent weeks.

Members who have sought to hold worship services have been briefly detained or confined to their homes.

Asked about the authorities' actions, Foreign Ministry spokeswoman Jiang Yu on Thursday avoided details, but said church members had been "gathering illegally many times and in order to keep social order, public security departments have adopted relevant measures."

The petition, drafted by senior underground church leaders Xie Moshan and Li Tianen and signed by 17 church leaders from six cities, is a strong indication of nationwide support for Shouwang's plight.

"With the incessant growth of the number of urban Christians and the continued expansion of the church, the conflict between state and church of this sort is likely to continue to break out," said the petition, dated Tuesday. It demanded that a law be passed to protect religious freedom.

The expansion and growing influence of house churches has unsettled China's rulers, always suspicious of any independent social group that could challenge Communist authority.

In southern Guangdong province, many security officers accompanied priests and lay people to cast votes Wednesday for Huang Bingzhang, 43, as the new bishop of Shantou, said ucanews.com, a news service that covers the Catholic church in Asia.

Huang, the only candidate, received 66 of the 72 votes, its said. Huang is a member of the National People's Congress and head of the government-controlled Guangdong provincial Catholic Patriotic Association.

Calls to the local religious affairs bureau rang unanswered Friday.

Local authorities had sought to appoint Huang for several years, but had been thwarted by opposition from local Catholics, ucanews.com said. The website is run by the Union of Catholic Asian News, based in Bangkok.

The Vatican-appointed bishop of Shantou, Zhuang Jianjian, has never been recognized by Beijing and has been under house arrest for over a month, it said.

China and the Vatican have no formal relations and even informal contacts have recently been testy. That is largely due to Beijing's insistence that it has a right to assign bishops through carefully orchestrated elections in defiance of the pope's authority to make such appointments.

An accommodation in which most new bishops received tacit approval from the Vatican appeared to break down last year. Chinese officials responded to criticism by accusing the Vatican of seeking to undermine the independence of the Chinese church and interfering in the rights of Chinese Catholics to practice their faith.

China says about 6 million Catholics worship in 6,300 official congregations across the country, although millions more are believed to worship outside the official church. China says almost half of the country's 97 dioceses lack bishops and that it intends to move quickly to fill them — with or without Vatican approval.

In a further sign of that determination, Li Zhigang — a priest with close government ties — was elected bishop of the southwestern diocese of Chengdu on Tuesday, ucanews.com said.