China is investigating the case of a bishop after he dramatically split with the state-sanctioned Catholic association over "serious violations" of rules, state media said Thursday.

Thaddeus Ma Daqin announced his break from the Chinese Patriotic Catholic Association during mass at his ordination as auxiliary bishop of Shanghai on Saturday and disappeared shortly after, according to Catholic media.

"The Shanghai auxiliary bishop ordination activity is suspected of seriously violating selection rules of the Bishop's Conference of the Catholic Church of China," China News Service quoted the association as saying.

"The Chinese Patriotic Catholic Association and the Bishop's Conference are now investigating and assessing," a spokesman said, according to the report.

No further details were given.

Ma told the congregation that due to his new responsibilities he could no longer be a member of the association, drawing loud applause from the assembly, according to a video posted online.

He was previously vice-chair of the association's Shanghai branch and was a member of its national standing committee, Hong Kong media reported.

An official of the Shanghai branch of the association contacted by AFP declined to comment and said he did not know Ma's whereabouts.

The latest development came amid growing tension between Beijing and the Vatican.

On Tuesday the Vatican had said it was excommunicating another Chinese bishop ordained last week by the state-sanctioned Church in northeast China without Pope Benedict XVI's consent.

China ordained Yue Fusheng in the northeastern city of Harbin on Friday, despite repeated warnings by the Vatican.

The association said the excommunication would hurt the development of the Catholic Church in China.

"The Holy See's statement (about the ordination) is not beneficial to unity with the Chinese Church and not beneficial to the healthy development of the Chinese Church," it said, according to China News Service.

China and the Vatican severed diplomatic ties in 1951 after the latter recognised the Nationalist Chinese government in Taiwan, a rival to the communist regime in China.

Although Beijing and the Vatican have improved relations in recent years as the Chinese Catholic population has grown, they remain at odds over which side has the authority to ordain priests.