(CNN) -- A newly appointed Catholic bishop who publicly resigned from the body that oversees China's state-sanctioned church has reportedly been detained.
Thaddeus Ma Daqin announced he was quitting all of his positions in the Catholic Patriotic Association (CPA) in his ordination speech in Shanghai on Saturday, the state-run Xinhua news agency reported.
"With this ordination, I will be devoting my heart and soul to the Episcopal ministry and to evangelism. Hence, there are some positions that will be inconvenient for me to hold on to. From today's ordination onwards, I will no longer be a member of the CPA," Bishop Ma told the congregation, in quotes carried by Xinhua.
The announcement, made in front of several state officials, was seen by many as a rebuke to China's communist rulers. Several news organizations, including the Catholic News Agency (CNS), reported that he was taken away and detained hours after his speech.
UCANews reported that priests and nuns in Shanghai have since received a text message from Bishop Ma's cell phone claiming to be sent by him. The author of the message described himself as being "mentally and physically exhausted" and needing "a break" to make "a personal retreat."
Various reports, unconfirmed by CNN, said Bishop Ma was being held at the Sheshan Catholic seminary, on the outskirts of Shanghai.
Both CPA and government officials said they were unaware of the situation when contacted by CNN.
While Ma was appointed by the Vatican, the Holy See has long been at odds with Beijing over the ordination of "illicit" bishops by the CPA, which it does not recognize. The CPA in turn does not recognize the authority of the Holy See.
On Tuesday, the Vatican announced that a Chinese priest in Harbin, northeastern China, Father Joseph Yue Fusheng, had been automatically excommunicated after being ordained without the Pope's blessing.
"The Holy See does not recognize him as bishop of the apostolic administration of Harbin, and he lacks the authority to govern the priests and the Catholic community in the province of Heilongjiang," the Vatican said in a written statement carried by Vatican Radio on July 10.
A close observer of religious affairs in China, who asked not to be identified, described Vatican-Beijing tensions over the ordination of Chinese bishops as "very worrying."
"We don't know how these things will be played out, if this will be tit-for-tat. It's quite unsettling," he said."
China severed formal ties with the Vatican in 1951, with worship only permitted in government-controlled churches. However, many of China's estimated 10 million Catholics are believed to have remained loyal to Rome, preferring to gather in underground "home" churches.
CNN's Tian Shao contributed to this report.